## Friday, September 04, 2009

### RWS Model LP8 Magnum - Part 3

by B.B. Pelletier

Part 1
Part 2

The .177 RWS LP8 pistol is a big, beautiful spring pistol.

Today, we'll look at accuracy for the RWS LP8 Magnum. It has a long and illustrious heritage to live up to, because the previous pistols from Diana have all been very accurate. We know from Part 2 that the pistol is powerful, though the Browning 800 Mag shaded it by quite a bit after I shimmed the breech seal. But this pistol is still a legitimate 700 f.p.s. air pistol!

Even BB can learn!
I hope you know that I don't know everything about airguns. And I hope you know that I sometimes make mistakes. Because I have a pretty big one to share with you today.

Remember all that talk about how to rest a recoiling air pistol? If not, read the report. Well, sometimes it doesn't work! And the LP8 is a pistol that doesn't like my way of holding a rested pistol. Allow me to explain.

I was testing another air pistol and getting groups that were strung out. When I shifted to the LP8, they were still strung out. But I know from experience that a Diana spring pistol is almost as accurate as a rifle, so I must have been doing something wrong.

Do you recall how I discovered the artillery hold for spring air rifles? By doing the opposite of what the Beeman catalog instructed. And the groups shrank up tight. So, I did the same thing with the LP8--I rested the barrel directly on the sandbag and the groups tightened up. Look at the difference I got while shooting Crosman Premier 7.9-grain pellets.

The 10-shot group of Crosman Premier 7.9-grain pellets from the hold described in the earlier report was this huge 2.603" vertical string.

I refined the hold from what I normally do to this one with the barrel rested on the bag.

And the second group of 10 Premier lites went into this group measuring 1.263". This is a significant improvement.

So, lesson learned! However, this does not negate that other hold, which I will always try first, before moving to this one. It does work on a great many pistols, just not this one.

Gamo Match
Gamo Match pellets proved to be the best in this LP8. Ten shots grouped 1.045".

Gamo Match was the best pellet tested.

RWS Basic
RWS Diabolo Basic were a surprise by grouping a whopping 1.795". Usually, RWS pellets are among the top for accuracy in a Diana airgun. Not this time, though.

RWS Diabolo Basic wadcutters shot this 10-shot 1.795" group. It was the best pellet tested.

Trigger
I noticed a lot more creep in stage two while trying to shoot accurately That always brings it to the forefront. And that screw we wondered about turns out to adjust the length of stage one, according to RWS USA.

According to the importer, this screw adjusts the length of stage one in the trigger pull.

Conclusions
So, the bottom line is the new LP8 is more powerful than the pistols that came before, and it still has great accuracy. It represents a lot of value in a spring air pistol, even at a price that is no longer considered inexpensive. If you're looking for a powerful spring-piston pistol, this one just might be the champ when all things are considered.

At September 04, 2009 7:08 AM,  Anonymous said...

What is the difference between the .177 RWS Club 10 pellets and the .177 RWS Diabolo Basics? From side by side inspection they appear identical, and their weights are the same. Does one go through more of a "selection" process?
thx

At September 04, 2009 7:44 AM,  Mr B. said...

Good morning B.B.,

WOW! I never thought that resting a springer's barrel directly on anything would improve its accuracy. Always something new to learn about our sport--keeps things interesting.

When you get a chance, what is the distance you were shooting at for the accuracy test? Thanks

Mr B.

At September 04, 2009 8:15 AM,  Anonymous said...

Hello all, it's Aaron up here in MI just counting the hours until my long weekend kicks off!! I haven't posted in awhile, but I've been reading right along. I've had a major change occur in my airgunning life recently. 2 weeks ago the spring on my RS2 broke, and the gun wouldn't cock anymore. This was very disheartening, so I got online to see what my options were for a replacement spring, and what I found wasn't a spring at all, but what I felt to be a tremendous deal on a brand new Benjamin Discovery, with the hand pump, in .177 caliber. Well I finally got the gun yesterday, topped it off with a Leapers 3x9x40AO scope, and I couldn't be happier. Yes it's loud, and yes the plastic trigger is stiff, but that is about all I would say on the some what negative side. On the positive, it is extremely easy to pump up, and probably takes less than a minute to top off. The accuracy at ten yards is phenomenal with CP heavy's. Probably the best groups I've ever shot in my life, with any gun. And the power!! I don't own a chrony, but this thing would blow the occasional shot completely through an inch thick pine board. The same pine boards my RS2 never shot through!! I was able to shoot about 40 accurate shots on a fill at 10 yards. I think that's tremendous, given you only have to pump for less than a minute to charge it up. The wood and metal were more than adequate for the price range of the gun. And the smallish size makes it shoulder like a dream. I know there are lots of mods that can be done to this gun, and some day, I may do them. But for now, I'm gonna shoot this baby as is, and hopefully continue to be immpressed. After today I've got three day's of shooting coming up in Northern Michigan (what some people refer to as "God's Country")and I'll be able to shoot at some longer ranges to see how the accuracy holds up.

I never thought I'd venture into the PCP world, but here I am. A special thanks to BB for raving about this gun so much!!

Take care gang, and have a great holiday weekend!!

-Aaron

At September 04, 2009 8:25 AM,  kevin said...

Aaron,

Sorry to hear about the RS2 but if it lead to the discovery maybe it was meant to be?

Glad to hear you're back shooting with a gun you're thrilled with. Take your time pumping, don't overheat the pump or you will burn it up. Have you watched B.B.'s video on pumping?

kevin

At September 04, 2009 9:16 AM,  Vince said...

Soooo.... Aaron.... whatcha doin' with the RS2???

At September 04, 2009 9:17 AM,  wayne said...

Aaron,

Nice move.. you'll be a happy air gun camper from now on.. Well until you want to move up to a quiet Marauder! But, not to worry, you can keep or sell the Disco when your ready.

The only mod you might need is an extra barrel band... or you could move the one on the gun out closer to the end of the barrel, if accuracy ever goes south..

Have a wonderful time this weekend in Gods country!.. I know I will!.. just a different part! ... I'm going up to shoot field target with the Washington state folks..

Wacky Wayne
Ashland Air Rifle Range

At September 04, 2009 9:19 AM,  wayne said...

Vince,

Fishing without a pole?

You'd be wise to bite Aaron...

Wacky Wayne

At September 04, 2009 9:30 AM,  Vince said...

Wayne, why on earth would I wanna bite Aaron???

At September 04, 2009 10:01 AM,  Anonymous said...

Vince - I was going to send it to you to fix!

-Aaron

At September 04, 2009 10:24 AM,  Vince said...

Good. I'd rather fix the gun than bite you. Sometimes I just don't know what Wayne is thinking...

Anyway, I'm thinking that a non-original spring (Norica or a Maccari E9870) might be best.

If you want, email me at vfblovesnancy@yahoo.com

At September 04, 2009 10:30 AM,  CJr said...

Mr B,
I left a rather lengthy comment for you on the Taiyo Juki post about the Talon SS and Ms. M.

-Chuck

At September 04, 2009 10:45 AM,  Anonymous said...

BB
Any word yet on those new optics you mentioned a while back.

Tiru

At September 04, 2009 11:37 AM,  wayne said...

Vince,

not even just a nibble and spit it out! jeesessesseeee what's the world coming to! But wait a minute.. you were the one fishing... and biting too???

Wacky Wayne... and who said I think!!

At September 04, 2009 12:33 PM,  Hungry Hippo said...

What does Aaron taste like?

At September 04, 2009 12:37 PM,  FRED said...

chicken

At September 04, 2009 12:40 PM,  Dino said...

The only scope mount designed to fit the 14mm rail on my Supersport (the B-square 17501) appears to be chronically out-of-stock. I'm thinking about trying a one piece Leapers mount, possibly after machining its base wider to fit the BSA rail. Has anyone tried one of these mounts on a BSA?

At September 04, 2009 12:43 PM,  Anonymous said...

Anonymous,

RE: RWS Club & RWS Diabolo Basics

So many pellets, so little time...

Same topic discussed in thread below with no real answer to questions. The thread also included RWS Hobby.

http://www.targettalk.org/viewtopic.php?t=22415&postdays=0&postorder=asc&start=0

There must be some difference...

Herb

At September 04, 2009 12:59 PM,  Anonymous said...

Thank you for your response to my RWS Basic vs Club-10 pellet question Herb.

At September 04, 2009 1:02 PM,  Anonymous said...

B.B.

The hold is a surprise. Since the rested hold is so aberrant, I wonder if the offhand grip is too. If I keep missing with my 1911, I may rest the barrel too.

Aaron, congratulations on your Discovery and thanks for the news about how easy it is to pump. When the original University of Notre Dame burned down, the president, Fr. Sorin, said it was a sign from God to build something bigger and better. I'm sure Vince can set up your RS2 and Rich Imhoff or Mike Melick could as well. You're not short of options to repair spring guns.

Jane, I don't know that women have a corner on impulse buys. You're quite the giant for the hand pump.

Herb, good, so now we see how the gun magazines are cutting corners even when they average numbers of five shot groups. The goal seems to be to juggle numbers to get everything MOA or close to it. I've been thinking about a quantitative reason why the multiple five shot groups are inferior to the 30 shot group. My intuition is that each group of five wipes the probability slate clean, but this isn't math. Now my idea is that the answer has to do with error calculations. There must be an error associated with a 30 shot group which would be small since this number is suppose to establish the Gaussian distribution. The comparable error for a five shot group would be much greater. To get a comparison, you add the errors for 6 five shot groups and compare to the 30 shot group. I don't know the procedure for this, but surely adding errors is not going to reduce them, so you will end up with a bigger error. A bigger error is precisely the space your outliers (of low probability) will fall into. That's why your multiple five shot groups is not as good as one 30 shot group.

BG_Farmer, you're right. Clint Fowler is a shooter and a fitter, tester, and assembler of barrels but he wouldn't know the details of their construction like Lilija. His comment about the unsatisfactory nature of a 6000 shot barrel, I think, is consistent with Lilija's high standards but the expertise is not the same. So, there is a value for bullet instability in the chart. Now that I think about it one doesn't need to discover a particular value. Any reasonable one will do as reference, and my guess is that the one he picked is reasonable for factory manufacture--probably better. His particular data still seems to me to suggest small diameter spiraling. Can you send me all the information you have about your American Rifleman article? My library has the magazine but not that far back. The strategy is to Google all available info to come up with an exact citation then order it through interlibrary loan. The ILL service can get it, but they need the exact citation.

Speaking of American Rifleman, their website has an article about the top 10 handguns of all time which is iconic in theme. All of my guns made the list: 1911, Colt SAA, Luger. The SW29 made it but not the Glock. There was no mention of the Makarov, so we know something the author doesn't.

Matt61

At September 04, 2009 1:56 PM,  Jane Hansen said...

No more discussion on spiraling..?

Gyroscopic precession occurs when any force tries to push a spin-stabilized projectile off of its axis of rotation.

For proof: A common grade-school experiment. Spin a bicycle wheel vertically at arms length, (hand on each axle end), while sitting on well-balanced on a bar stool. As you tilt the wheel, it will spin you around in the chair. (you are now a spiraling pellet).

So now, we're on Jupiter. The target is 50-yards away. To hit the target, we angle the barrel up almost 45-degrees, just to overcome the massive gravity.

The pellet emerges at a 45-deg angle, but essentially travels somewhat horizontally, to hit the target. The pellet is spinning off-angle to the flight path.

This is how all projectiles fly: A modified parabolic trajectory, but basically angled-up ever-slightly to the flight path.

Back to Jupiter:
Our Jupiter has atmosphere - the pellet is flying into air resistance, the dome is heavier than the tail, the tail is also sometimes ribbed, grooved, or patterned. In any event, the force on the tail is more effective than the force on the dome, and the pellet is being forced to rotate "off-axis".
Thus: the spiral.

The disturbing note here - perfect rifle, perfect pellet, same effect. (but, quite consistent).

In the real world, at close range, the angle of elevation is minimal, the force differential on the pellet negligible, the consistency is good, the net effect virtually undetectable, we adjust for it, and never notice it.

NOW, push out to 50+ yards, a larger, slower pellet, 650FPS. The story changes. We need to overcome 9" of drop, the angle is high, the wind has time, and the spiral becomes almost visible....

Still, it's consistent, and we can compensate, until we start hunting. The range, elevation, and wind are never the same, and we only get one shot. And even though we were sighted in perfectly at 50-yards, we miss clean at 60.(I miss for many reasons - but this makes me feel better).

How to overcome.......

??

At September 04, 2009 1:58 PM,  Anonymous said...

Hungry Hippo,

There's was news recently about a circus dwarf killed in Pattaya, Thailand. He bounced sideways off a trampoline right into the mouth of a yawning hippo who was waiting for the next act. The hippo swallowed reflexively and that was it.

Matt61

At September 04, 2009 2:12 PM,  Anonymous said...

Jane,

There's a lot going on in this experiment. I'm a little puzzled at the Jupiter scenario. If a pellet is fired at a 45 degree angle, why would it fly horizontally? If massive gravity is pushing it down, shouldn't it keep pushing it down past horizontal?

For a parabolic arc on Jupiter or anywhere else, wouldn't you expect the axis to coincide with the flight path? The axis should correspond to the tangent to the curve so while the flight path is changing, the axis coincides to the flight path at any given moment.

The differential force on tail and dome would throw the pellet off and cause a spiral, no doubt. But surely pellets would be designed for even forces; they don't commonly fly nose up like this do they? It sounds like individual faulty pellet design.

For range correction, I recommend a variable AO and a ballistic chart or extensive practice estimating bullet drop. For the wind, the David Tubb methods of wind reading.

I wonder if I have missed your point.

Matt61

At September 04, 2009 2:23 PM,  Anonymous said...

Matt,

RE: 30 shot group vs six five shot groups

Any two points determine a straight line perfectly, a quadratic equation (ax^2 + bx + c) can be fit to three points and so on. So as I calculate more numbers to fit the data, I'm losing information on the errors in the data.

If you take the average POI of the 30 shot group or the average of the POI for the six 5 shots groups you get the same number.

However if you take the group size (essentially a standard deviation) of the 30 shots and the average of the six 5 shot group sizes, then you will get a different number. In statistics this has to do with what is the "degrees of freedom."

Think of one 5 shot group. What is the "true" POI from which you ought to measure the error distance? Unless God whispers it in your ear you don't know. So you approximate the "true" POI with the average POI which you measure from the 5 shots. But taking the average essentially POI costs you a data point. So the group size is essentially based on 4 shots not 5.

So essentially since you have six average POI & group sizes, you "loose" shots. So one 30 shot group actually has 29 data points for the group size, and each of the six 5 shot groups has 4 data points. But 6*4 is only 24! So the average group size for six 5 shot groups would be like shooting one 25 shot group.

Now there is a small wrinkle. As I remember the costs of 1 shot for the average is an approximation and not theoretically exact. Close enough again. Obviously the average group size of thirty 1 shot groups is a lot different than the group size of a 30 shot group.

To go further, let's analyze a 5 shot group "properly." In statistics you use a "confidence interval." Say you want to be right 95 times out of a 100 which is typical. That's about two standard deviations on the Gaussian curve.

Let's assume that I get a group size of 0.38 inches for one 5 shot group. Now I want to extrapolate and determine what the "true" group size would be if I shot an infinite number of shots. I also want to know what the upper and lower limits for 95 out of 100 such measurements.

The experimental distribution around 0.38 is skewed. It can't be Gaussian since I can't get a negative group size. I could easily have a group size of 2 inches though.

So all in all, I lookup fudge factors in some statistical table. The fudge factors say that I need to multiple 0.38 times 1.25 to get best estimate for the average of an infinite number of shots, and 1.93 to get high side confidence interval, and 0.78 to get low side interval. So I end up with:

0.475 +.733/- 0.296 with 95% Confidence

So what this means is that 95 times out of a hundred that the measured group size would be between 1.208 (0.475+.733) and 0.179 (0.475-0.296).

Now I just made up the fudge factors in the above example, but the factors do illustrate the notion. The fudge factors do also correctly show that there is a considerable amount of luck for a 5 shot group.

As the number of shots in group increases towards infinity, both fudge factors will change and move towards 1. A sample size of 30 is typically deemed "good enough" to be an infinite sample. So the fudge factors for a sample size of 30 would be 1.

Now this analysis isn't quite right since you don't actually use the average POI for the traditional way of measuring group size. But such a measure is implicitly included. The traditional way of measuring group size also isn't the way statistics is usually done, so the three "magic tables" of fudge factors don't exist to my knowledge. But overall I've outline the notion. Does this make the whole thing a bit clearer?

Herb

At September 04, 2009 2:29 PM,  twotalon said...

Jane....
One thing I have found over the years that helps in understanding things that sometimes don't seem to work as they should....

Take things to the extreme!!

It makes it easier to see what happens when you switch from the ideal condition to a severely wrong condition. An in-between condition becomes more understandable.

By the way, this discussion has gone on since July 17. Wonder if that is a record?

twotalon

At September 04, 2009 2:35 PM,  Volvo said...

Wayne,

Jane,
While I remember making tie dye t-shirts in grade school, I must have been absent on bicycle tire \bar stool day. Very regrettable I must say, as it would have been fine training for my twenties.

Anyone,
So last night I’m flipping channels when I stumble across the last few minutes of “Shane”. Since the family was all out of the house, what followed was inevitable. I found myself with a holster strapped to my leg and my trusty Ruger Single Six loaded with CB longs. The Beeman silent trap “never cleared the holster” as I drilled it reapedly with about 50 rounds. One thing I have always wondered is why one handed accuracy is so much better for me with a single action vs. other types of handguns?

Volvo

At September 04, 2009 2:53 PM,  Jane Hansen said...

Matt:

The point, (what the Jupiter experiment should enable us to envision), is that the axis of rotation is NEVER in line with the flight-path.

Even on earth, the pellet leaves the muzzle with a slightly elevated angle. It doesn't ever fly where it was originally pointed, (unless there was no gravity), so that "launch vector" is out of alignment as soon as the trajectory starts to flatten out.

If we DO try to correct the angle in-flight, we introduce precession and spiraling. In fact, current pellet design does exactly that - the added resistance, (and lower weight), of the tail attempts to keep the pellet in line with its flight path. I guess pellet designers know that "spiraling" is a lot less problematic than "wobbling." Equally important, precession is consistent, generally insignificant, and we zero-in without ever noticing it.

"Real" bullets make no attempt at in-flight correction. They are of uniform density throughout, and resist wind equally from head to tail. Real bullets plow into their targets at the exact angle they leave the muzzle, regardless of whether the trajectory was rising or falling at impact.

(I hestiate to call it "nose up" because in fact it's only a few milliradians, but, on Jupiter, "nose up" would be correct).

My dream is that some day, Tom Gaylord will do for airgun trajectories what Fabrique-National's 5.7 did for handgun trajectories - flatten them out.

To hunt succesfully I use the heaviest, most solid, (most "bullet-like") projectile, and fire it as fast as possible.
This minimizes the angle, and minimizes wind-effect.

The challenge is the transition-zone at 1100FPS. For longer ranges, staying on the high-side of supersonic is a whole lot better that flying on the low side.

Best regards,

Jane Hansen

PS- Not being a giant, I fight every day with "the pump". I am not heavy enough to push the handle, and have resorted to a very comical, but effective, leverage method.

At September 04, 2009 3:11 PM,  Anonymous said...

Jane,

Wouldn't you agree that in order to spiral that the pellet must be precessing?

Since you can't measure and correct for spiraling, the object is to choose a pellet which precesses the least. The problem is that there isn't any way to measure precession directly.

Using group size and/or POI shift would be an indirect measures.

Maybe for hunting you also need to measure POI shifts over the range which you would hunt. If you're going to hunt between 30 and 80 yards, how about measurements at 30, 55 and 80 yards. You measure not just group size, but POI shift - particularly horizontal shift. You might then end up choosing a pellet which has a slight larger group size at 30 yards, but which doesn't curve as much horizontally at 80 yards.

Pragmatically you can't adjust some parameters such as the rifling twist. You're left with shooting and measuring.

Now if you could measure precession directly, then you could perhaps play with some of the setup factors for a gun like the Benjamin Marauder. It seems quite possible to me that a the gun could be adjusted to shoot a given pellet optimally. This would be the opposite of having the setup fixed, and then choosing the optimal pellet. The point is that you'd pick a setup which minimized precession. A couple of shots would give you a good measure of precession, but if you were measuring the group size and POI, then you'd have to shoot a massive number of shots to get useful data.

Make sense?

Herb

At September 04, 2009 3:29 PM,  Anonymous said...

Jane,

I guess my point is that I was really surprised to see that there could be a considerable POI shift between two different types of pellets. I zero target at 10 meters for one type, then shoot second type of pellet. The POI typically shifts.

No doubt that the pellets are traveling along some curve - above and beyond what simple ballistic corrections for gravity would predict.

Some time ago I naively thought that you could standardize on say JSB exact then measure POI shift for each pellet type relative to JSB. The problem is that I switch rifles, and the POIs for different types of pellets shift again but in a different way!

Herb

At September 04, 2009 4:03 PM,  Joe B. said...

BB, I wonder what the result would have been if you'd rested the frame, not the barrel or your arms, on the rest?

At September 04, 2009 4:11 PM,  Jane Hansen said...

Herb:

I think you are correct. POI shifts are induced for a variety of reasons, my guess is precession isn't a problem until 2 things are happening - we're out long, (needing more of an angle), and we vary distance with every shot. (precession is very consistent, but if the spiral is large, POI shift in just a few feet could be dramatic.

.177 cal. becomes preferable for many reasons - flatter trajectory, less angle, less "face-to-the-wind", etc.

I can only surmise that the barrel/pellet combination that is most accurate, by trial and error, is minimizing precession, magnus, and a variety of forces.

Much as I think I know what should work better, I don't know anyway to get there but by trial and error...

Jane Hansen

At September 04, 2009 5:18 PM,  Anonymous said...

Jane,

Overall I'd agree that if everything else stays constant then the precession would stay fairly constant. So you could correct for precesion while target shooting, but it would be impractical as you pointed out for hunting.

However I'd think that a pellet which is precessing also has a smaller ballistic coefficient than if the same pellet were not precessing. So all in all, it seems that precessing is bad and should be avoided if possible.

Of course every pellet would precess to so small measure. The gist is is the precession causing problems? - and how do you figure that out??

Although the shape of the pellet could change sound levels, I do think that you could detect precession sonically. You'd have to use a fast sample rate, a parabolic reflector & microphone, and Fourier analysis.

The normal twist rate I think is 1 turn in 16 inches. So 900 fps would be 675 revolutions per second as BB blogged on August 20, 2007. I'd think that the precession rate would be lower. Of course if the precession rate was a harmonic of the spin rate, then Fourier analysis wouldn't work.

Microwave Doppler radars are outside of most of our budgets...

Maybe something could be gleamed from measuring the ballistic coefficient multiple times over distance. With a smooth bore would you get any precession? So with smoothbore as gold standard to measure BC, you then measure BC for rifle. If the the rifle's BC is significantly lower would it be reasonable to assume that the rifle pellet was precessing? BC does change with velocity itself, so you'd have to find a distance where smooth bore and rifle had about the same velocity.

Do you think that either of the two methods would likely yield useful information?

Herb

At September 04, 2009 5:23 PM,  Mr B. said...

CJr,

I think we crossed posts on yesterday's blog.

Jane,

The old timers were masters at judging range to target, knowing the trajectory of their chosen round and doping the wind.

Aaron,

Welcome to the wonderful world of the PCP. Nice to hear from you again. You're right about the Discovery's size and hunting with it.

Mr B.

At September 04, 2009 5:24 PM,  BG_Farmer said...

Jane,
Now I believe you are a rocket scientist:). I mentioned the tilt in passing as an unavoidable cause of precession or gyration last night, but I was already in too deep:). You did a better job anyway.

If I understand it correctly, a higher spin rate introduces more dispersion at longer ranges (i.e. steeper trajectory), due to the variance in angle that you described. Spin rate is controlled by two things primarily: velocity and twist. Lowering velocity to lower spin rate causes a steeper trajectory, so that is not ideal. A reduced rate of twist might be worth looking at.

I don't mean to be a crank with this, but it does seem that this aspect of air rifles has been largely ignored, perhaps because the most demanding and high-paying users until very recently were only concerned with accuracy at 10M. The rest, hunters, FT shooters, and benchresters, either had to make do with what they got.

At September 04, 2009 5:33 PM,  BG_Farmer said...

Matt,

I still feel bad about Clint Fowler, but if he reads the blog, I hope he'll forgive my hyperbolic rhetoric:).

I'll try to find the exact title of that article (easy search didn't turn it up fast). E.H. Harrison, Nov. 1965 is the only citation given, but there's also one from July 1962 that discusses twist rates and stabilization also; I mention this not to confuse the issue but to point out that it may be a tangled mess to plough through:).

At September 04, 2009 5:40 PM,  Anonymous said...

Herb, I remember "confidence interval" and while my grasp of it was always shaky, I believe it is the concept I am searching for. While there is an error associated with individual data points. I don't know that there is an error in the same sense for a whole group. Confidence interval must be the right concept. If the confidence interval associated with a 30 shot group is smaller than or at least different from that for an aggregate of 5 shot groups that makes things clearer. Thanks.

Matt61

At September 04, 2009 5:48 PM,  Anonymous said...

Jane,

I think I am confused by the terminology. I consider the flight path to be the parabolic arc followed by a projectile. The straight line coming out of the bore I call the boreline. At the muzzle, the flight path and boreline coincide. But right away, they start to diverge with the boreline angled slightly above horizontal while the flight path starts to bend under the influence of gravity to form a parabolic trajectory.

I can see why the axis of the pellet would start to diverge from the boreline, but why would it diverge from the flight path? When a football is thrown, the nose starts to drop to keep the axis of the football coincident with the flight path. That's what I pictured pellets doing. What would be the advantage of designing pellets to fly in a nose-up attitude which would definitely cause the axis to deviate from the flight path?

I also don't understand the difference between spiraling, wobbling, and precession. A nose-up attitude means that the point of your pellet is elevated above the flight path. Precession means that the pellet point is revolving around the flight path. I don't see how you can have both at the same time.

Matt61

At September 04, 2009 5:55 PM,  Anonymous said...

BG_Farmer,

Nothing to feel bad about. You're exactly right that barrel manufacturing is not Clint's specialty and he would be the first to agree.

Name and date are good progress for the article. I'll do some searching but not this weekend. :-)

Matt61

At September 04, 2009 6:03 PM,  Anonymous said...

Jane, I forgot to ask. What did FN do to flatten handgun trajectories? All you can do is increase the powder charge and improve the bullet BC right?

Also, have you tried putting your bodyweight into the pump stroke? B.B. recommends this and so does heavyweight legend Jack Dempsey who says that power is derived from "putting your bodyweight into fast motion" with the aid of gravity.

Matt61

At September 04, 2009 6:07 PM,  BG_Farmer said...

Matt,
Thanks. I'll find the article title somehow and appreciate your help when I get a good reference.

Jane, etc.,
Just so I don't appear to be jumping on the bandwagon, when I said I mentioned tilt I though it was true, but I probably should say I thought about it and remember typing something about it, but I am getting old and I can't find it now:). No matter, just don't want to be dishonest.

At September 04, 2009 6:34 PM,  Jane Hansen said...

Matt:
You're close. Let's use your terminology.
The pellet emerges from the muzzle spinning in alignment with the boreline. Gravity causes the trajectory, (flight path), to deviate substantially from the boreline - the barrel, (and boreline), are aiming up; the trajectory, after reaching it's peak, is actually aiming down.

The pellet was spun aligned with the boreline. Ideally, it WILL NOT diverge from this angle. Because the angle is so slight, we are better off if the pellet keeps spinning in alignment with the boreline. If it stays that way, there is no force causing precession.

If ANYTHING tries to move the pellet off of its axis of spin, gyroscopic precession will take effect, thus, as the aerodynamic forces start to align the pellet with its flight path, it inherently forces it into precession.

It's really a trade-off. Without some sort of attempt to keep the pellet "nose-to" it will get buffetted by countless other forces we don't talk about, and wobble off-course. This is why we spin it to begin with.

Gyroscopic precession is the movement a spinning body undertakes in response to off-axis forces. We see it as "spiraling". There are other causes of spiraling, (and other forms of precession).

Wobbling is erratic fluctuations in pitch and yaw. This is worse than spiraling, as the spin becomes tangential to the air, magnus forces can actually cause the pellet to change direction. At least when a pellet is spiraling, it generally spirals around the "intended" flight path - the groups open up, but the pellet hits the target. Wobblers can go anywhere.

best regards,

Jane

At September 04, 2009 6:43 PM,  Anonymous said...

Matt,

RE: 30 shot groups & six 5 shot groups

I was trying to explain too much perhaps.

The "confidence interval" discussion was intended to show how you should correct one 5 shot group to the group size for an infinite number of shots. You could correct a 3 shot group, a 5 shot group, a 10 shot group, and a 30 shot group all to the infinite group size for comparison. Say I shot a 5 shot group with one type of pellet and a 30 shot group with a different type.

The problem between the 30 shot and the six 5 shot groups is "degrees of freedom."

It is easier to discuss this in one dimension so let's talk about muzzle velocity. God knows that the true muzzle velocity and standard deviation are 500 fps and 20 fps. That is what I get if I take an infinite size sample. But what happens if I sample 5 shots?

In order to calculate the standard deviation of the 5 shots I have to calculate an experimental average over the 5 shots. That effectively reduces my sample size from 5 shots to 4. Now if God told me that the true average was 500 fps, then I could keep all 5 measurements when calculating the standard deviation for the 5 shots.

So for a sample size of N, I end up with N-1 degrees of freedom for the standard deviation calculation. as N approaches infinity, the difference between N and N-1 gets smaller and smaller.

But again, you have to be careful. Is there some hidden factor in the grouping? Six different shooters? Groups shot on six different days? Six different types of pellets? Groups of 5 sequentially six different times? Also the discussion ignores what to do with fliers.

So "better" is relative. You have to be careful to understand the circumstances under which "better" would apply.

Herb

At September 04, 2009 7:14 PM,  ajvenom said...

Let's make it simple. On the day you plan to shoot, try every pellet closest to the time and place you plan to shoot, zero in and go.

I'm giving up on physics and statistics. My old physics book sits in my desk out in my garage and makes and excellent wheel chock.

For me, I had good luck with the .22 Predator Polymags, Eun Jin 28 and 32gr pellets in my Discovery. Surprisingly, the Polymags may be the most accurate so far in my Discovery, but time will tell.

At September 04, 2009 7:20 PM,  Mr B. said...

BG_Farmer,

I'm with you--twist rates need to be studied.

Mr B.

At September 04, 2009 7:24 PM,  Anonymous said...

Jane,

Thank you, much clearer to me and clarifies my questions. Why must a projectile precess for its axis to remain aligned with the flight path? Going back to football, it's plain to see that many extremely long passes with the ideal tight spiral (which would correspond to "spin" in bullets/pellets) and with a fairly pronounced trajectory have the nose following the flight path. Is there something wrong with the analogy between footballs and spinning pellets?

The preferred method you are describing with the nose up seems to describe overstabilization in firearms bullets as I understand it where the spin is so high that the bullet will keep its orientation through the trajectory causing the axis to deviate from the flight path. This overstabilization is undesirable for bullets, so why is it an advantage for pellets?

Herb, what is a degree of freedom? Is it 29 for a 30 shot group and 4 for a 5 shot group? I see that a five shot group is less reliable than a 30, but the means for comparing aggregates of 5 shot groups with the 30 is not clear to me. It's probably something I would have to spend a lot of time with a book to understand.

Matt61

At September 04, 2009 7:36 PM,  Herb said...

RE: Confidence Interval

Assume that you shoot a 5 shot group of 0.38 inches.

There is some information missing. If you shoot another 5 shot group, then what would be the expected group size?

That is where the confidence interval comes into play. Let's say that the measurement with confidence interval was:

0.38 +.20 inches/-0.13 inches @ 95%

That would mean that 95 times out of a hundred that the group size for 5 shots would be between 0.58 inches and 0.25 inches.

It obviously isn't "fair" to shoot a hundred groups of 5, then choose the best group as being "representative." Shooters don't generally go to that extreme, but I'd venture to say that it would be common to shoot multiple groups of 5, then use the best group size. That practice is really a lie, and depends on heavily on pure chance. With such a practice, the "best" group size would be much smaller than the "average" group size.

Again, so far as I know there isn't a table to look up the fudge factors to convert the number of shots, and the measured group size into a confidence interval.

Statistically the group size isn't really a standard deviation but a range value. Similar, but not the same thing.

The other thing to appreciate is that the group size throws a lot of information away. The group size only depends on the two widest spaced shots. Such a measurement is heavily weighted towards fliers. You could have 99 shots in a 0.25 inch hole, and one shot 2 inches out. The group size is then 2 inches. You throw out the the flier, and the group size shrinks to 0.25 inches. So how to treat fliers needs to be defined carefully, and not just guessing. No doubt that shooters are prone to throw out shots as fliers, when the shot really isn't a flier at all.

Herb

At September 04, 2009 7:42 PM,  Jane Hansen said...

Matt:

The projectile precesses as it aligns with the flight path because it is changing its axis of spin. (ANYTHING that moves the projectile of its original spin axis will cause precession).

The football analogy is a great one - because footballs DO NOT align with their flight path - they stay spinning in the same axis they leave your hand, (they never "nose-in" to the ground - in the best passes, the ball's orientation remains perfectly horizontal even as the pass rises and falls).

Fabrique National solved the angle problem. The 5.7 flies at 2000FPS, (1800 for "sporting rounds"), muzzle velocity. It's a virtually flat projectile at all practical distances. No deviation between boreline and trajectory.

Jane

At September 04, 2009 7:54 PM,  Herb said...

Matt:

RE: Degree of freedom

You use the degrees of freedom in the confidence interval calculation. More degrees of freedom essentially means that the confidence interval is smaller.

So for the standard deviation measurement based on a sample size of 30 shots, there is one average and 29 degrees of freedom. Six 5 shots groups have 5 averages (one for each group) and thus only 24 degrees of freedom.

So essentially the average of the six standard deviation measurements for the 5 shot groups would be like shooting one 25 shot group.

Now I have been wishy washy about degrees of freedom in group size because the group size is a range value not a standard deviation. Off the top of my head I don't remember if the range values follow exactly the same rules for calculating the degrees of freedom as standard deviations or not. But the notion is certainly right. The average group size determined from six 5 five shots groups will be smaller than the group size for one 30 shot group. The best group size from the six 5 shot groups will be even smaller.

This help?

I perceive that you're trying to learn something, and I'm more than happy to keep posting until you understand. I really wish that I could find the right tables for "fudge factors." That would help clear things up. Hand waving and making up numbers really obfuscates the ideas. I can find range charts in one dimension, but not two.

Herb

At September 04, 2009 8:23 PM,  B.B. Pelletier said...

Mr. B,

10 meters.

B.B.

At September 04, 2009 8:26 PM,  B.B. Pelletier said...

Aaron,

Now you can help me spread the word!

B.B.

At September 04, 2009 8:32 PM,  B.B. Pelletier said...

Tiru,

I examined those scopes in detail and they didn't measures up. I had to recommend no buy for all of them.

At 16 X they magnified the same as a Leapers on 7 power. No sale!

B.B.

At September 04, 2009 8:35 PM,  B.B. Pelletier said...

Joe,

I tried the frame. It doesn't work as well. The barrel works best.

B.B.

At September 04, 2009 10:49 PM,  Anonymous said...

B.B.

I'm looking forward to the micro Desert Eagle. If that is now your carry gun it must have surpassed the Taurus 1911 and the Makarov.

Herb, thanks for your help. I think I've gone as far as I can for understanding the details of the confidence intervals. But even from a distance I have a misgiving that I will share. The average of six 5 shot groups, as I understand the confidence interval business, should have an equivalent reliability as one 24 shot group. But the average of six 5 shot groups is generally a heck of a lot smaller than one 24 shot group. This doesn't sound right, does it?

Jane, this really changes the way I see football. Are you serious? I know that even with the monster throwing arms on the field now that quarterbacks have to throw at a considerable trajectory for the long bombs--no doubt up to 45 degrees. So, you're claiming that all long bombs thrown at that angle land in the receiver's arms downfield pointed 45 degrees up? Has anyone else noticed this? Throw some footballs on Labor Day and tell me.

For pellets there could be a practical test. If the pellets maintain a nose up attitude, then they should be keyholing when they hit the paper to some degree. It will be slight but there must be some distance at which it is noticeable. If 100 yards is one fifth of the maximum distance requiring a 45 degree trajectory, the elevation of the barrel for a 100 yard shot should be something like 10 degrees. Is that right? If so, this should produce a perceptible keyhole. Have you found that for long-distance shooting with your pcps?

Also, how can a pellet be nose-up and precessing at the same time? Nose up should be nose up while for precessing, the nose goes up down and around. These things seem incompatible.

I'm away for the weekend and will check back. Happy Labor Day.

Matt61

At September 04, 2009 11:09 PM,  DB said...

B.B.,
My friend. You must elaborate on the the "no buy" on the scopes.

Is this the stuff you taunted us with months back?

DB

At September 05, 2009 4:38 AM,  B.B. Pelletier said...

Matt,

The Micro Desert Eagle is not a better shooter than a Makarov. It is less accurate, slightly less powerful (it's .380 ACP, which is close to the Mak 9X18 mm round, but the smaller Micro has a shorter barrel) and it's harder to handle in recoil.

But the one saving grace the Micro has it its compact size. It is extremely small and flat. I tried carrying the Mak in an ankle holster for awhile, but it felt funny. And I had to wear long pants. I can slip the Micro in the front pocket of anything including a swimsuit (maybe not a Speedo, but nobody wants to see me in one of those, anyway).

I will not tell you the rest of the story now, because this comment will turn into a blog if I do, but trust me that I have tested or examined a great many small cary guns before reaching this conclusion. And until the Micro tests out reliably, it's not over.

B.B.

At September 05, 2009 4:46 AM,  B.B. Pelletier said...

DB,

Indeed, these scopes are the very ones I taunted you with from the NRA Annual Meetings in Phoenix. Chuck saw them, too.

I wanted the internal scope level very much, as I still do, but not so much that I will accept an inferior scope. If the power settings engraved on the objective lens are incorrect, I lose ALL confidence that the maker has gotten anything right. What if the 1/4-minute clicks are really 1/7-minute?

I talked to the owner of Leapers last week at the Pyramyd Air Open House in Cleveland, and I once again hit him with my request for an internal bubble level scope. He acknowledged in front of witnesses that I have been asking for the same thing for many years, and he said he would get on it.

The other scope that I rejected was a pistol scope that PA dearly needs. It is too large, but worst of all the retail would have to be $20 higher than the much smaller BSA pistol scope they already sell. I can't see where that is anything they can sell. So, no buy! B.B. At September 05, 2009 5:03 AM, B.B. Pelletier said... Jane, I don't know if Tom Gaylord can flatten out airgun trajectories like FN did with the 5.7 round. He's more likely to come up with a heavy solid "pellet" that can be loaded into most airguns without extreme pressure. More of a Chanel No. 5 approach (making solid pellets less stinky to load). Looking at your postings on the pellet spiraling thread, my wife, Edith, says I owe you something for writing a better blog than me. I just caught up to the current discussion and I must say I think I agree. You are a great asset to this blog. You make me want to ask Tom Gaylord to develop your special gravity-defying pellet. Now, where did I put that Unobtainium?. B.B. At September 05, 2009 6:29 AM, Vince said... Matt61, I think you'll find that a 45 degree launch trajectory maximizes distance only in a vaccuum. If air resistance is present, I think you need to launch at less than that to get the longest range. At September 05, 2009 8:39 AM, Herb said... Matt, Again, I'll apologize for being obtuse. There are three different quantities being calculated. First is the group size itself. The average group size of 30 shots would be larger than the average of six 5 shot groups. Second, the average POI. The average POI of the 30 shots, and the average of the average of six 5 shot groups would be the same. Third and lastly is the variability of the group size. I was calculating standard deviations to stand in for group size. There is a measurement known as the radial standard deviation which has been used in shooting circles. However group size is really a range measurement. It is the variability of six 5 shot groups that would be similar to the variability of multiple 24 shot groups. Even this analogy may not be exact since the analysis was for standard deviations not group sizes, but the notion is right. The variability of the group size as determined from six 5 shot groups would be greater than the variability of numerous 30 shot groups. There is something else here to appreciate. A single group size measurement does not carry any information about its variability. You'd have to measure group size a number of times and determine a standard deviation. However if you measure the radial standard deviation of the shots, then the radial standard deviation can be manipulated to calculate a confidence interval for the variation of measuring the radial standard deviation. Herb A country preacher arrives at church one snowy January Sunday morning, to find only one person had braved the cold to come to the service. The pastor greets the old farmer and asks if he should go ahead with the service. The old farmer replies, "Reverend, if I go out to feed the cows and only one cow shows up, I still feed her." The Reverend thinks this is pretty good reasoning, so he starts the service with a few hymns, followed by a morning prayer, scripture reading, an offering, a sermon, invitation and closing hymn. At the conclusion of the hour-and-a-half service, the farmer doesn't move. Ok, thinks the Reverend, and he walks to the back of the church and opens the door. At this point the old framer gets up and starts to leave. As he shakes the Reverend's hand, the Reverend asks the farmer what he thought of the service. The old farmer replied "Reverend, said I feed her, didn't say I'd feed her the whole load." Matt - if I had any idea that I was going to confuse you so badly, I'd given you the whole load the first time! ;-) At September 05, 2009 9:00 AM, Herb said... BB (or anyone else), Know anything about RWS wad cutters? RWS seems to have a number of 7.0 grain pellets varieties (with different prices) which appear to be vary similar. Is the primary difference quality control (QC)? There are RWS Diabolo Basic, RWS Club, RWS Hobby, and RWS R 10 MATCH which seem to be the same pellet. See: http://www.rws-munition.de/en/sports_airgun/rws_airgun_pellets.htm?navid=33 QC does seem a reasonable explanation. There have to be some dies involved which wear. Make highest quality pellets for a while, then after the die wears use same die to make more "lower" quality pellets. Also for high quality pellets to take more measurements for quality control. The very best pellets, RWS R 10 MATCH, also do come in various head sizes. That doesn't seem to be offered for the Basic, Cub or Hobby varieties. PA has, per tin of 500 7.0 grain smooth wadcutters: RWS Club - 5.98 RWS Diabolo Basic - 5.99 RWS Hobby - 6.59 RWS Meisterkugeln Pistol - 9.15 RWS R-10 Match - 12.59 Don't know if PA gives you a choice of head sizes in Meisterkugeln or R-10 match. Herb At September 05, 2009 9:04 AM, DB said... B.B., Too bad about the scopes. Internal level would be helpful for paper punching. Jane & Herb, WOW!!! Might have to print this out and read it again in a week. Though I do get it. I use the take to extreme technique also; usually works well for technical and even sometimes for politics. People can usually see the mental picture of extremes. DB At September 05, 2009 9:17 AM, Herb said... RE: flatten out airgun trajectories like FN did with the 5.7 round My 2 cents... Assuming that it could be done, is it really safe? The point of airguns with a diabolo pellet is that the pellet doesn't carry too far. If you shoot a "pellet" (aka a bullet) at 2000 fps with a airgun, yes it will have a flat trajectory. But it will also carry like a firearm. That does skirt the present laws about pellet guns, but such an airgun would likely hasten new laws. No doubt our poorly informed Congress would impose some Draconian definition on airguns. Just look at Canada, England and so on. So such a development doesn't seem desirable. If you want that kind of power, use a firearm. If you can't use a firearm for the particular application, there is probably a good reason. I believe that the bigbore airrifles are creating a scenario that endangers the distinction between airguns and firearms. For now the big bores are exotic handmade items. But the PCPs are closing the gap. It seems that we need to control our desire for power lest we force more legislation. Right now a pellet gun is considered a toy, and not a "real" gun. Let's keep it that way. Herb At September 05, 2009 9:55 AM, BG_Farmer said... BB, The scope manufacturers seem to be "consolidating" sources and designs into only their best sellers; lower magnifications seem to be going by the wayside: my local Walmart doesn't even carry a 4x of any type in a 1" tube anymore, and they would laugh about 1.5 or 2.5X. I've never used a Leaper's, but many of them look exactly like some of the better Tascos (Golden Antler AG, World Class), which are pretty good. Example, the Leaper's Golden Image 3-9x32 seems identical (except for flip up covers) to the Tasco Golden Antler, which has to be the gold standard for a tough, cheap scope, laugh if you will. I'm surprised that Crosman/Centerpoint doesn't have a reasonable pistol/scout mountable scope. The multi-pumps would seem to demand these as much as pistols. I'm almost willing to bet there will be a movement back towards lower, fixed or low-range variable magnifications and smaller objectives at some point, mainly because they are in fact useful and more suitable to some purposes than the bigger is better philosopy that is driving us now. At September 05, 2009 11:06 AM, BG_Farmer said... Herb, I believe the Diabolo Basics used to be called Geco's. They vary from the Hobby superficially by the lack of a fluted skirt (Basics have a smooth skirt, like the MKS). They are sold as 7gr., but as you pointed out, the weight is nominal. I also suspect they vary in head and skirt size from Hobby, Club, MK pistol, etc., but have only seen a specification in one place, which I don't want to link here. Like you, I do suspect the pellets spec'd at 7 gr. vary in head and skirt size for service in a variety of rifles. I don't think the "low-line" varies internally in QC -- and Basics shoot very well in my 2 lower powered rifles, although I would expect the MK and R-10's to have better QC or come from more frequently replaced dies. At September 05, 2009 11:28 AM, Anonymous said... Herb. My 2 cents. You hit the nail on the head. The last thing we need is more legislation. Hank At September 05, 2009 12:29 PM, Cougar94 said... Hello,B.B Someone here in South Africa (where i live) recommend the Leapers 5th Gen 3-9X50A0 Scope for my Diana Panther 34 (known here as the Diana Panther 31). My Question is: Would the diameter of the lens (50mm) not be too big for my airrifle when used with the Leapers "Droop Compensating Mount" I am concerned that the lens would touch the "body" of the airgun and get damaged during recoil. Would the use one a one piece mount with Leapers "Droop Compensating Mount" be overkill?(I want the scope to have maximum protection against the recoil of my Diana) Thank you, Cougar94 At September 05, 2009 12:50 PM, Anonymous said... BB! Look what I found on gunbroker! http://pics.gunbroker.com/GB/139121000/139121091/pix741314703.jpg Does umarex have a rimfire section of their web site? Shadow express dude At September 05, 2009 12:52 PM, Anonymous said... Cougar94, Leapers True Strength scopes are built to take the recoil of the most violently recoiling airguns ever made--the Webley Patriot, which broke just about every scope mounted on it...except a Leapers. Tom wrote an article about the toughness of Leapers True Strength scopes. In that article, you'll see that even a hammer can't break their scopes. The Leapers 5th Gen 3-9x50AO scope you're referencing is a True Strength scope & will stand up to the comparatively mild recoil of the Diana 34. Edith At September 05, 2009 1:43 PM, Jane Hansen said... B.B., Herb, et al: I believe you are "on" to something. Our current selection of pellets does not seem right for higher-powered PCPs. The skirt, waist, and moment of inertia seem all wrong. The design almost would better in a non-rifled barrel, where tail-drag would be the primary stabilizer. Same goes for the barrels - at 900FPS they spin these pellets way too fast. The combination almost invites wild spiraling. What's the point of high-powered PCPs, if a CP only flies straight at half-power? (I tried RWS superdomes - they aren't good till you wind them down to about 650FPS) I find Eunjin's relatively stable at full power in the AA, but no way in the Infinity. I start on low-power there for multiple reasons. I don't know what the legal ramifications are, but does anyone sell a more "slug-like" pellet? Soemthing that maybe has a boat-tail fin and is more cylindrical in shape? regards, Jane Hansen At September 05, 2009 2:01 PM, Herb said... RE: RWS pellets Fun Easter Egg hunt. Found three tables on the web. I have no idea how accurate any are, or how much they copied data from one to the other. http://www.luchtbuks.net/index.php?showtopic=709 http://straightshooters.com/documents/pelletcomparison.html http://www.airgunexpo.com/airgundb/pellet.cfm The RWS Meisterkugeln Pistol & the RWS R-10 Match have a length of 0.222 inches compared to about 0.210 inches for the RWS Club, RWS Diabolo Basic and the RWS Hobby. Between the RWS R-10 Match and RWS Meisterkugeln I'd guess difference is quality control. R-10 a hair better probably. I'd GUESS that the R-10s get made on new dies and Meisterkugelns get made after some wear. Different packaging as well. R-10s no doubt get kid glove treatment. As BG_Farmer pointed out the RWS Hobby has a fluted skirt as compared to the RWS Club, and the RWS Diabolo Basic. Couldn't find any difference between RWS Club, and the RWS Diabolo Basic. There must be something... I'm somewhat confused about weights. The RWS website lists 7.0 grains for all, yet the tables have weights all over the place. http://www.rws-munition.de/en/sports_airgun/rws_airgun_pellets.htm?navid=33 I'm also skeptical about 0.001 inch differences in dimensions in the tables. Unless the measurements are done with same technique and same measuring equipment errors can easily creep into data. Herb At September 05, 2009 2:27 PM, BG_Farmer said... Herb, I think you're right about the R-10 -> Meisterkugeln connection. You hit the jackpot, but I share your skepticism:). Jane, When we've discussed this issue before, the conclusion always seems to be that some spin is better than none even for Diabolo, but after reading the Lilja article, I'm fairly convinced that the spin, if any, should be much slower than a "real" bullet. I still don't understand what positive effect spin has on a diabolo, aside from a hopeful "evening out of the imbalances" (which would be fine if it worked that way). The practical issue is that there's probably no way to get a high quality smooth bore air gun in a popular caliber (.177 would be ideal) at a reasonable price to test. The Crosman 760 is available in both, but the price point alone invites cynicism. The Gamo Shadow Express is probably slightly better, but its a springer and that is not ideal for extreme accuracy testing, either. Regarding velocity only, 900fps seems to be the upper limit of the safe zone for diabolo design, due to buffeting in the transonic zone, although perhaps excessive spin coupled with miserable BC's exacerbates that tendency? I know I've gotten excellent results at the standard 50yds. with hi-velocity .22LR's which stay in the "danger zone" pretty much the whole time of flight, although I realize they are a different design and stabilized differently. They are not, however, ballistic superstars:). And, the prevailing wisdom is to stay subsonic for maximum accuracy even there. At September 05, 2009 3:06 PM, Herb said... Jane, Very interesting observation about your power settings and the spin rate. Maybe at 900 fps the twist rate ought to be 1 in 32 inches, or more, instead of the 1 in 16 inches which I think is normal. It does seem reasonable that there would be a trade off between spinning fast enough for additional stability, and not so fast as to precess madly. Compared to round ball ammo, I was amazed as to how well diabolo pellets shot in a cheap smooth bore Crosman 760. I have no experience picking pellets for a PCP, but the Eunjin seems to be about the heaviest pellet, 28.4 grains, and has the highest BC of any other pellet. See for example: http://www.straightshooters.com/ourtake/ottesteunjinsumatra.htm With the PCPs you have, it seems that you have about as much power as a 0.22 firearm. For a 0.22 long rifle http://books.google.com/books?id=b5bnsE500FMC&pg=PT106&lpg=PT106&dq=%220.22%22+%22ballistic+coefficient%22&source=bl&ots=_jKEgP3etc&sig=vUsOj6Z2ZsmgUMeE1KdFQMwARfw&hl=en&ei=p76iSuXyG5CJtgfa59HYDw&sa=X&oi=book_result&ct=result&resnum=9#v=onepage&q=%220.22%22%20%22ballistic%20coefficient%22&f=false on page 118, the BC is listed at 0.140 with muzzle velocity of 1080 fps. (Weighs about 40 grains?) A 0.22 LR bullet would be too big for a 0.22 pellet rifle. Maybe get some 0.22 slugs, grease 'em up, and swage them through a die to reduce diameter down a couple of thousandths? Herb At September 05, 2009 4:42 PM, Herb said... Jane, Search on "Eley Wasp Magnum" you'll get a lot of hits for UK sources. I'm guessing that this bullet was the subject of the spoon seating discussion in BB's blog http://www.pyramydair.com/blog/2007/08/daystate-saga-part-2-story-continues.html BB notes that the bullet is actually oversize for a 0.22 pellet barrel. Ran across an interesting site with cross section pictures of various pellets. http://www.photosbykev.com/wordpress/nggallery/post/air-rifle-pellet-database/album-19/gallery-276/ "Eley Wasp Magnum" is pictured at... http://www.photosbykev.com/wordpress/nggallery/post/air-rifle-pellet-database/album-19/gallery-179/ Herb At September 05, 2009 5:19 PM, Anonymous said... Herb, Thank you again for the effort you put into answering my question of: "What is the difference between the .177 RWS Club 10 pellets and the .177 RWS Diabolo Basics? From side by side inspection they appear identical, and their weights are the same. Does one go through more of a "selection" process? thx " My main quandry was when I did a visual comparison between the .177 RWS Club and the .177 RWS Basic, they appear identical. Not similar, but identical. Your web links offer information that the RWS Club may have a larger head size and skirt diameter than the RWS Basics (Geco). So that may be one difference not distinguishable via the naked eye. Your web link directing me to RWS' ammunition site (www.rws-munition.de) suggests that the Clubs and Basics may be in a different "class". The Clubs being an economical "proven training pellet" (for target shooting?), and the Basics being described as an economical "pleasure shooting pellet" (for plinking?). I guess the only thing I need to worry about is how they shoot. If they offer up the same accuracy, then it is moot. When PA is out of Clubs, I'll order Basics. When out of Basics, I'll order Clubs. thx At September 05, 2009 6:12 PM, Anonymous said... Jane, The "H&N Rabbit Magnum" II seems interesting. it is a bullet not a pellet. See picture at: http://www.airgunbuyer.com/Showproducts.asp?cat=Pellets&SubCat=Pellets Herb At September 05, 2009 7:22 PM, Volvo said... Herb, Someone just tried the H&N Rabbit Magnums on the yellow forum and reported disappointing accuracy. If you would like to try them, they are available in the states. I pondered getting a tin until I say the accuracy results from barrels designed for pellets. At the end of the day, most Diablo pellets seem to prefer nothing over the mid 900’s, which has lead to continuingly heavier pellets as air rifle power has increased. So I guess for real speed, you need a powder burner. At September 05, 2009 8:24 PM, Anonymous said... B.B., I am fairly new to springers - I bought a Quest 800 two months ago to try it out - but have a Crosman 1322 that I have shot off and on for decades. I’ve been reading this blog for weeks and practicing, and I am finally starting to get the hang of it. I’ve put about 1500 rounds through it now. While my best 10 shot groups at 20 yards with 15.8 grain JSBs still run just a little over an inch, I do get 5 or 6 of them within half an inch, sometimes a quarter inch – so I feel the gun can be accurate once I get consistent. I do enjoy it, and plan to keep at it. But I’ve hit a problem. Today, after shooting about 10 pretty good groups, my shots all started moving upward on the target over about 15 shots or so. Then they settled in at the new POI and grouped about the same, but about 3 inches higher than before. I thought the problem was with the scope (a Leapers 3-12X44AO with about 600 shots – the 4x32 died at around 700), but it is with the gun. I re-zeroed and then shot another group at 40 yards, and through good old physics (no Chrony yet) found that I’m now down to about 510 fps, when I was at about 730 fps before. When I took the stock off, I found that I can use a screw driver to move the mainspring and piston back and forth about half an inch while the gun is uncocked – plus when I break the barrel, it now droops to about 45degrees freely which it never did before. So I’m pretty sure the spring is broken – but it still shoots. What I am wondering is pretty simple – in your opinion, should I send it back to Pyramid for warranty service or send it to a tuner for a full overhaul? I’m sure the service route is cheaper, and I could save the money and put it toward another gun, but I think the gun would be much better if tuned – and the truth is it was already better than my skills. Let me know what you think. This is simply an awesome blog. I continue to read all the prior postings and comments. I look forward to being able to contribute in the future. Alan At September 05, 2009 8:26 PM, Mr B. said... Jane, Thank you for your explanation to Matt starting with ...and lets use your terms.It caused an awakening deep within some rusty corner of my brain and a practical understanding of what you all have been talking about for a couple of years. Long, heavy for caliber bullets are what the long range powder burners use.65-80 grains in .224. They all require a faster twist rate to be stabilized, something in a 1-6 or 1-8 range. Has anyone made a barrel for a PCP with a similar type twist and tried shooting long heavy for caliber cast lead bullets??? We'd love to hear from you. Jane, a thought for your hand pump. Make a base for it that allows your feet to be a true sholder width apart and you'll find using it becomes alot easier. Mr B. At September 05, 2009 8:30 PM, B.B. Pelletier said... Cougar94, The mount will elevate the scope high enough for the bell to clear the gun, but you may want to get the 460 mount with less elevation. Ever since that 34 mount came out the 34s are seeming to droop less than they did before. The 460 mount may be enough for you. B.B. At September 05, 2009 8:33 PM, B.B. Pelletier said... Jane, I will answer your pellet question/posit with a blog, because the answer deserves greater attention than just a comment. This coming week... B.B. At September 05, 2009 8:39 PM, Jane Hansen said... Mr.B. I just don't weigh enough for the pump. I saw a very strange You-tube "Dirt E. Harry" review of a pump - and he used a piece of wood as a lever. I've refined the idea a little with a 12' long 2x4 pivoting on one end screwed to the inside of a door frame. It's a bit tedious, but I have some ideas for improvement... B.B. said we'd see a$500 compressor. I'll be first in line.

Regards,

Jane

At September 05, 2009 8:43 PM,  Anonymous said...

B.B.,

Alan here - one last thing on my Quest 800. I already upgraded it with a GRT-III trigger. That was a big improvement when I made it.

Alan

At September 05, 2009 9:40 PM,  BG_Farmer said...

Mr. B,
The .223 idea is basically what will work, if people want to take air rifles there, but there may be problems due to the reduced heat and pressure (which are also benefits). For example, will it require driving bands and/or gas check, since the lead (assuming a boattail) won't obturate at current pressure for PCP's (need > 7000 PSI)? How about that type of bullet with synthetic driving bands or sabot-like skirt to engage the rifling? Looks like a lot of the black powder bullets are using those types of techniques.

At September 05, 2009 10:05 PM,  Vince said...

Alan, the 800X can be an excellent gun - running well, they are pack a good amount of power into a compact, lightweight package. Additionally Crosman is excellent when it comes to parts support for these things in terms of both availability and price.

Unfortunately, though, manufacturing quality's been spotty. It used to be that the Quest springs (available from Crosman for about $6) were very reliable, but over the past year or two I'd been hearing more about spring breakage. I've also seen rough compression tubes which can cause a seal to wear prematurely. If you send it back for repair, you'll get the factory questionable parts and the rest of the gun might not be 'all it can be'. Worse yet, they might replace it with another one that might not shoot as well for you. So if the basic gun seems to shoot well for you I'd keep it and repair it. You'd wind up with a much improved gun that you already KNOW will be accurate. And if you have a better grade spring installed (like a Maccari E3650) you'd gain reliability. But why not take a 'shot' at it yourself? At September 05, 2009 10:29 PM, Herb said... Granted a typical 0.22 firearm isn't the ultimate in accuracy, but I assume that typical air rifles have same twist rate. Thus it would seem that if you could get a 0.22 PCP going about 900 fps with a bullet, then it ought to be roughly similar to a 0.22 firearm. A bullet would be heavier than a pellet, so it might require a faster twist rate to stabilize since the velocity might be much lower than 900fps. Not sure how fast Jane could push a 40 grain(?) bullet. Might be interesting to try some heavier bullets/pellets at full power just to get rough idea of muzzle velocities. Fill something like 0.22 Defiant pellets with Pb/Sn solder to make them even heavier? You'd need a scale to weight them. This of course also ignores friction. Since there is more contact surface, a bullet would have more friction going through the barrel than a pellet. At September 05, 2009 11:00 PM, Mr B. said... Evening B.b., Have you looked at the Kel-Tec P3AT in .380 auto and if so would your share your opinion of it with me? Thank You Mr B. At September 05, 2009 11:42 PM, Mr B. said... BG_Farmer, I think you're right. We should really look at black powder guns for ideas. Big bores should be looked at like Kentucky Rifles. What more power use a bigger heavier bullet cause 1200 fps seemed to be about it. Sorta seems like that's where we're currently at with our PCPs. You're also right when you're talking the benefits of fixed power scopes--4x normal, 6x big game long distance and 10x varmit scope. Come you hunters out there, what power do you have your 3x to 12x set at when hunting? I'll bet that it's no where near the 12x. Mr B. At September 06, 2009 3:52 AM, Anonymous said... WARNING RANT!! In the airgun community there is a line that is being pushed and sometimes even stretched that we should all stop and take a look at before the line breaks! Most airguns and diabolo pellets,because of their design,are low powered short distance arms.The short range and rapid loss of speed and power make them almost perfect for the niche that they fill. That is they are fairly quiet and have less potential for collateral damage compared to firearms.Which means in a lot of cases they are less regulated because they are seen as less dangerous. With the trend for making more powerful airguns comes the wants of some to have long range pellets to hunt more and larger game,or to consistantly hit targets at what are effectively PB ranges.SO far the fact is that diabolo's don't do well at or around the speed of sound,so people are experimenting with pellet designs.I think that's just human nature to want more and better of something,but in this case it's going to cause problems for a lot of folks. What happens is that Diabolo pellets get replaced with bullets.That effectively erases the line between airguns and firearms. If you won't admit that this is going to lead to regulations,then I think you are being stubbornly naive. I know there are lots of us who just like to speculate on the what ifs,but there is a large group of airgunners who want the benefits of what is basically an unregulated firearm.Without regaurd to what it's going to cost all of us in the long run. I know it won't happen because regs usually have such broad strokes but.... I really hope that when the axe falls it misses those of us who use and enjoy pellet guns for what they are,and hits those who want benefits without cost. Because those people are puttting the cost on everyone. In short if you want PB power,then go to the trouble to get a PB and save the rest of us a lot more trouble in the end! I don't think I'm in the minority,I know from reading the blogs that I'm not the only person who feels this way. I'll shut up now and I'm in my bunker awaiting incoming.Fire away JTinAL At September 06, 2009 5:56 AM, B.B. Pelletier said... SED, Sorry that I missed your link to the .22. I don't know if Umarex has rimfires on their website, but I just tested a Colt M4 rimfire made by Umarex. It will be in a feature article in Shotgun News in November (the 20th). B.B. At September 06, 2009 6:17 AM, B.B. Pelletier said... JTinAL and Jane Hansen, Well, JTinAL started my blog answer about pellet designs. I'm still going to blog it, but he hit the nail on the head. Once you start shooting solid bullets, you have left the world of airgiuns as they were originally designed. Whether this is wrong or bad is a separate issue, because the bigger issue is what is possible with just air--I think. We have Dr. Frankenstein building humans out of spare parts, causing a huge discussion on the technology of human-building, but also causing another bigger discussion on the morality of building humans. Just because a thing is possible doesn't mean we should always do it. Yet the pursuit of science says we should always try to do something, so we know where the boundaries are. But when we do that, the boundaries always advance and change. In the solid-bullet discussion, it is the individual airgun experimenters, not the manufacturers, who are leading the science. We live at a time when the factories are being led (technically) by their customers. Detroit says they make concept cars to test different approaches before committing to production. On one hand Chrysler makes a turbine sedan in 1953 that never goes into production. On the other hand Ford makes a 4-cylinder Mustang concept car that meets with such acclaim that they start a whole new classic car line within a few years. Well, listen to this. The Benjamin Discovery was the concept of an individual (me) that the factory (Crosman) tentatively tried. When it worked beyond their wildest expectations, they jumped in with both feet and build the Marauder, the Challenger 10-meter PCP, the Field Target Challenger, the PCP pistol that is soon to come and maybe other PCP designs so fantastic that you won't believe them until you see them. So the customer is leading the airgun development world, because Ray and Hans Apelles are at the forefront of Crosman's PCP advances today. Once the genie is out of the bottle there is no way to put it back! B.B. At September 06, 2009 6:31 AM, B.B. Pelletier said... Mr. B., Yes, Edith owned a Kel-Tek 9mm, which is much like the .380 and only slightly larger and more powerful. It couldn't get through one magazine without jamming. I shot several boxes through it before trading it away. The Kel Tek design has a serious flaw. Once the trigger is pulled one time you have to stop and cock it again before you can pull the trigger again. While it qualifies as a DAO action, it is a quirky one that I would not trust my life to. The Micro Desert Eagle is a true DAO and you can keep pulling the trigger and the hammer keeps falling. So, if the problem is related to a primer misfire, you have a second chance. Granted that is a very low fraction of the operational problems you can expect to encounter, but if the rest of the function is reliable (I'm testing that right now), then the gun is better, in my opinion. The Kel Tek .380 has a large and faithful following. But when I pushed every owner I met, I learned they all had some reliability issues. And I know the slightly larger 9mm we had was a sick puppie. What I need is the physique to carry a larger pistol like the Makarov that is dead-nuts reliable. But alas, I am built like a bobber and have to carry something that fits in my pocket. B.B. At September 06, 2009 6:39 AM, B.B. Pelletier said... Alan, Without question you have a broken mainspring on the Quest. If you like the rifle in all other ways, I vote to have it tuned. But my real advice is to move on. I advise getting an RWS Diana 34 or a Gamo Big Cat. These are springer that are worth investing time and money in. Or, consider the Crosman NPSS. You get a lightweight tuned rifle with a potentially great trigger and it's scoped right out of the box for under$300. I just came from a shoot where a GIRL (Crystal Ackley from American Airgunner) hit silhouettes at 50 yards offhand with her NPSS.

This may be the investment point required to get a rifle that you can live and grow with.

B.B.

At September 06, 2009 9:29 AM,  Herb said...

RE: 0.22 bullet with PCP

I really doubt that a PCP can be made to fire like a 0.22 rifle. If it does then JTinAL is absolutely right that the difference between a pellet gun and a firearm has been erased.

First I think that in terms of ft-lbs of energy that the PCP is underpowered compared to 0.22 firearm. 1/2, or less, at the present time?

But that compares the kinetic energy (KE) of a pellet to a bullet. But if you compare the KE of a 40 grain pellet to a 40 grain bullet, you are comparing apples and oranges. The bullet will have a lot more surface area of contact with the barrel. So the friction will be much higher for a bullet compared to a pellet. The result will be a massive drop in muzzle velocity and KE for the bullet.

You might be able to make it work with something like a Skeenco round with a plastic sheath to reduce friction. But the sheath has to stay on the bullet for a rifle with a shroud. A sabot will expand on leaving the barrel muzzle and get hung up in the baffles on a shrouded rifle.

The science does fascinate me. But I'd guess that a plain lead 0.22 bullet though a PCP would have a disappointing low muzzle velocity. So in order to stabilize the round you'd need a faster twist rate than the current barrels have. But what is the point of having a high twist rate barrel to shoot a 0.22 bullet at 500-600fps?

In fact I think that the big bore rifles have already crossed the line. Fortunately however big bores are expensive exotic air rifles. The current line of PCPs are pushing the envelope. But Lewis and Clark had a PCP! So it isn't really "new" technology.
The other saving grace is that big bore rifles are as big and as noisy as a firearm.

So for a few experiments we don't run much of a risk of wiping out the line between firearms and pellet rifles.

At September 06, 2009 10:32 AM,  B.B. Pelletier said...

Herb,

When you say "...like a .22 rifle." you are really saying like a .22 long rifle cartridge, because that is the one with the 40-grain bullet. The .22 short has a 29-grain bullet and uses a twist rate of 1 in 22", though you'll never see a new one today. We have standardized the long rifle and forced the short to conform to the 1-16" twist rate, which it does well enough.

The Condor is MORE powerful than the .22 short, standard speed (60 + foot-pounds, compared to 55 foot_pounds), but it doesn't stop there.

Van Jacobi at Airhog has created a .25 caliber Condor that gets 110-120 foot-pounds of energy at the muzzle with a 40-grain pellet. He uses a 28-inch Lilja barrel and a retuned Condor valve to make use of the extra 4 inches of push.

120 foot-pounds in where a standard-speed long rifle cartridge is, so we are knocking on the door right now. Don't expect things to remain static, either.

B.B.

At September 06, 2009 11:03 AM,  BG_Farmer said...

Mr. B,
If only they could make a PCP as attractive as an old Kentucky:).

Herb,
Half is more than halfway there, given that it's v^2. Good point about the shroud and sabot. I've got some ideas, but JT reminded me that I don't really like the concept of pushing airguns any further anyway.

JT,
You're right. Interesting theories aside, I would rather have a springer (or even other pneumatic design) well below 900fps and use it without worrying. I think you hit the nail on the head with the bit about people wanting an unregulated firearm -- like that would last for long. If I want or need a firearm, I use one.

At September 06, 2009 11:12 AM,  Bub said...

The website for the Umarex Colt 22lr rifles is www.colt22rimfire.com.

Bub

At September 06, 2009 11:54 AM,  DB said...

All,
Fear not research on conical bullet style pellets.

The power plant (air supply and valve – in the PCP world) are the limiting factor. No doubt someone could or has put together PCP’s that will push a 30-grain bullet out the barrel at 1,500 fps. But unless it has a really big tank the number of shots would be very limited. Of course then there is the refill effort in terms of hand pumping or running for the big air tank to consider. This greatly reduces the risk or danger associated with it. You can not load up 15 rounds in 1-minute or drop in a new 9-shot clip in 2-seconds. So a PCP could never be as dangerous in terms of mass destruction.

Having said that… the people that make laws are not always logical. Sometimes they try to ban guns because they have a pistol grip stock or are painted black. Then there are SCOTUS (Supreme Court Of The United States) members that look to laws of other countries for guidance and most of those countries already consider low powered airguns too dangerous.

The risk of law changes is already there. Designers tinkering with a few ultra high powered and ultra expensive hobby air guns are not making much of an impact. The risk is there with or without airgun design changes.

DB

At September 06, 2009 12:02 PM,  Mr B. said...

BG_Farmer,

Have you ever been to Williamsburg, VA and watched the period gunsmiths make a Kentuckey flint lock from scratch? A wonderful way to spend a couple of hours.

Lets take the big bores to another level and put an effective LDC on them and get them sounding like a Maraurder. Wonder how long they would have to be?

Let's look at black powder guns from 25 years ago and today's sabot firing 250 yard rifles which haven't resulted in any regulatory changes that I'm aware of. Maybe a good comparison between today's PCPs and what the tech guys have in the pipe line for tomorrow's PCPs.

I for one say bring them on!

Mr B.

At September 06, 2009 12:10 PM,  DB said...

All,
Like many I purchased my Disco to fill a niche. There are places where a 22 cal is just not safe to shoot... especially if when pointing up into a tree.

If it is safe to shoot a 40-grain bullet at 1500 fps then grab the 22-LG. It is less costly and generally more accurate anyway. Noise level is about the same and the 22-LR is a whole lot less work.

So... more powerful airguns are not a worry. It is just a novelty item that is not too likely to take off. That is unless someone figures out how to store 20,000 psi in an air tube.

My Disco, like many out there, is tuned to shoot slower than stock so as to make it more safe, quieter, and less work.

DB

At September 06, 2009 12:17 PM,  DB said...

Mr B.,
Good point. Black Powder (BP) guns are very similar in performance to high power big bore air guns.

Both have limited firepower. Both can be made as mult-shot repeaters. I have a six shot BP revolver. Actually you could probably reload the BP revolve faster than recharging a big bore PCP with a pump.

But... as stated those making or interpreting laws are not always logical.

DB

At September 06, 2009 1:03 PM,  BG_Farmer said...

Mr. B/DB,
I don't think the step over the edge is as far off as you think. Until somewhat recently, the difference b/t mere rimfires and commonly available pellet rifles was an order of magnitude more or less; now it is much less with some really "simplistic" engineering (higher pressure and better valve control, like running voltage at the upper end to allow a higher clock rate).

Add the novice shooter's fascination with reapeating actions (look, its another AR-15!), and there's the makings of trouble already. My core belief is that responsible citizens don't need laws, but reality tells me that there are more than enough irresponsible citizens that we will all get them whether we need them or not.

Muzzleloaders are limited by their very nature (and legal definition), and that seems to be enough (good point, however, about the BPR, shhh). Airguns are only limited by physics, ingenuity, and restraint at the present time. I worry that restraint is the weak link:). I agree that regulation always looms, but making it easier for idiots to be idiots just hastens the day. The number of Americans who have any sense of liberty and personal responsibility seems to shrink by the day, anyhow, so that the number of people who would trade freedom for safety or abuse their freedom with risk to others grows.

Mr. B,
I need to do that Williamsburg trip again. My wife is a William & Mary graduate and we have friends in the area, so it will happen at some point.

At September 06, 2009 2:09 PM,  DB said...

BG_Farmer,
Given the nature of those in control today... airgun regulation is the least of our concern.

BTW... not talking of any particular party or person. Instead speaking of the collective of our political leaders both elected and otherwise.

Hope still exists,
DB

At September 06, 2009 4:14 PM,  Hungry HIppo said...

I want to see a company come out with a Colt Single Action Army pellet gun.

At September 06, 2009 5:28 PM,  Mr B. said...

Hungry Hippo,

Enter your request in the searh feature of this blog. You'll see what you're looking for.

Mr B.

At September 06, 2009 6:56 PM,  Jane Hansen said...

While you all debate politics of higher powered PCPs, I just want a pellet designed to shoot in the current crop.

(somehow, with things like the SamYang Big Bore, and Career DragonSlayer, (190ft-lbs!) I think if "they" were going to restrict air-gun sales, they would have done it by now...and some state already do)

The diabolo is a drag-stabilized design that is perhaps simply outdated . My guess is the originators weren't thinking of safety, transition speeds, or anything other than trying to find a projectile that worked in older rifles...

I found the "Prometheus Pile-driver" which seems like it might fly in a high-powered PCP like the Infinity. Has anyone tried one?

regards,

Jane Hansen

PS - it is time to rotate out my collection of real fire-arms and bring in a new .45; Anyone have a preference for HK? Mark 23 or USP Elite??

At September 06, 2009 7:25 PM,  Jake said...

The Mark 23 is just a souped up USP .45, so...

At September 06, 2009 7:30 PM,  Jake said...

By the way, I left that statement ambiguous because they're both fine HK firearms, and I don't know what your looking for. If you want a "fun" gun, I'd say whichever's cheaper.

At September 06, 2009 8:56 PM,  Volvo said...

“Speed is poor substitute for accuracy” …this was in my fortune cookie today.

At September 06, 2009 9:43 PM,  Herb said...

RE: Diabolo pellet

Who invented it and when?

At September 06, 2009 10:09 PM,  wayne said...

Jane,

I still didn't notice your response to Kevin and my suggestion to try the JSB 18gr. for your high power desires..

or the Kodiak 21 gr.

Not that I think it will give you what your looking for... I still say keep it under 900fps.. and go with heavier pellets..

Try the DAQ 9mm air guns. I haven't tried them myself, but on the yellow forum, Rick Peterson has, and is working on what seems to be your goals..

I still don't know why in your situation, (noise and neighbors not an issue)...you don't just use .22 rimfire shorts.

Volvo,

Wacky Wayne

At September 06, 2009 10:26 PM,  wayne said...

Field Target report..

I went to Washington State this weekend, and shot with some of the top Washington shooters..

Bottom line, Nikko Stirling "Nighteater" scopes are not worth it... either save up for the "Diamond" or stay with the Centerpoint or Leapers line at half the price...

After missing my first shot, I cleaned the course up to the second standing lane. They had moved the course indoors, for fear of rain, and this lane had the light out.. So it was dark.

Lesson # 6,000,208,699,001 in learning field target, is "if the target is in a dark area, then turn down your power on your scope".
Kind folks they are, it was at least a minute after they should have called time on me, while I stood there saying "I can't see it", they said, try turning down the power on your scope... well, it worked..
..but by then I was shaking like the fall leaves outside.. and missed all four.. four of the total five I missed for the day!

Noel - 37/40 Washington State champ
Rick - 36/40 Runner up last year
Brent - 35/40
Wacky Wayne 35/40

Close but no cigar!!
but next week is coming soon..

Wacky Wayne
Ashland Air Rifle Range

At September 07, 2009 4:39 AM,  B.B. Pelletier said...

Hungry Hippo,

Here you go:

http://www.pyramydair.com/blog/2009/07/fanner-50-part-2.html

http://www.pyramydair.com/blog/2005/07/crosmans-single-action-six-another.html

B.B.

At September 07, 2009 4:41 AM,  B.B. Pelletier said...

Herb,

I don't have a name for the invention of the diabolo, but the time was before 1909 and probably after the turn of the 20th century. The country was probably either England or Germany.

B.B.

At September 07, 2009 4:45 AM,  B.B. Pelletier said...

Wayne,

Getting skunked in FT. Now, you're learning!

Been there; done that; got the T-shirt.

B.B.

At September 07, 2009 9:11 AM,  wayne said...

B.B.

Thanks, great to know I'm in such good company!

Where do I get the "Tee" shirt? :)

In that dark lane, with the top finishers, only one score was made out of 16 tries! ..and that was by the winner! The skunks were really smelly on that lane! But skunks, squirrels, or raccoons.. no matter, this is a darn fun game!

Wacky Wayne,
Ashland Air Rifle Range

At September 09, 2009 9:55 AM,  Anonymous said...

Jane, et al

One can compute a confidence interval for any statistic, including the range of a sample, though a statistician might prefer some measure less prone to influence by outliers, such as the interquartile range. The key element for computing the confidence interval for ranges is based upon the previous observation that a range cannot go negative: instead of a normal [Gaussian] distribution, the range can be modeled by the log-normal distribution. Just use the logarithm of each range value to compute the mean and standard error of the transformed range; then the confidence interval of the logs can be transformed back to inches plus or minus using the anti-log.

Berthoud