by B.B. Pelletier
Today I’ll look at the accuracy for the Walther Talon Magnum. You’ll remember that this rifle is the .177 caliber version of the Walther Falcon Hunter, which comes in .22 and .25 caliber.
The first step was to mount the scope that comes with the rifle. It’s a 3-9×32 that has no parallax adjustment, so whenever you shoot closer than about 25 yards you dial the magnification down until the image becomes clear. The scope comes already inserted in one-inch rings, so all you have to do is mount the rings on the base that’s on the spring tube of the rifle.
The scope rings are already installed on the scope. The bases have no scope stop, but you can use the stop on the rifle base.
The rifle base is a strangely notched 11mm dovetail. It would seem that these notches have a purpose, but they don’t work with any scope mounts we know of. The scope stop plate is a plain plate screwed into the top rear of the base.
The scope mounted with the reticle aligned correctly and the rings attached with slotted thumbscrews, so the job was quickly finished. Use a coin to tighten the thumbscrews.
Holding technique
I knew from testing the Walther Falcon Hunter that this rifle doesn’t respond to the artillery hold. This one wants to be held firmly, like a deer rifle. My range was 21 yards and I began the test with Beeman Kodiak pellets. The rifle was on paper in three shots, and the scope adjusted fine. The optics were not as clear as I would like, but you can always upgrade the scope later.
Kodiaks settled into a 3/4″ group. The rifle wants to be held firm into the shoulder and a firm grasp on the forearm, and then it will become very predictable. I also tried Crosman Premier 10.5-grain heavies, but they didn’t group as tight as Kodiaks.
A typical group of Beeman Kodiaks looked like this at 21 yards.
As I shot, two things became clear. First, the trigger was getting smoother very fast. I could actually sense it becoming smoother as I shot, so it probably won’t take but about 500 shots to break in all the way. The second observation is that the scope mount screws need constant attention. They loosen from the harsh vibration of each shot.
I tightened the stock screws just once and was surprised to find that the forearm screws have a LEFT-HAND TWIST! The triggerguard screws are right-hand.
RWS FTS pellets
I also tried RWS FTS pellets. They’re an older domed pellet that weighs 10.5 grains. But they weren’t even on the paper at 21 yards, and since the other pellets were, I didn’t adjust the scope to get them on.
JSB 8.4-grain domed pellets may be best
I ended the test with JSB Exact 8.4-grain domed pellets. They grouped about the same as Kodiaks, on average, but one group was tantalizingly tight.
JSB Exact 8.4-grain pellets grouped about the same as Kodiaks at 21 yards.
This one group of JSBs was much tighter than the rest. I don’t know what caused it, but with more testing this may prove to be the best pellet for this rifle.
The bottom line
Some of you have to shoot a .177 caliber rifle because of legal reasons. If that’s the case, this one’s a real bruiser. But if you can shoot a .22 or .25, I would go with the .22 caliber Walther Falcon Hunter. I say that because there are more good .22 caliber pellets available than there are .25s, and they’re less expensive. And the .22 produces so much more energy than the .177 in a powerful spring rifle like this.
But if you’re going to hunt with a .177 breakbarrel, this one offers a lot of value for a very low price.
I’m not surprised that you’re recommending this series of rifle in .22 – seems the natural choice (over the .177 and the .25) precisely for the reasons you state. But, if I’m not mistaken the .22 is the one variant you didn’t test…. or did I miss something?
Vince,
You’re right. I tested the .25, because it is the only .25 springer on the market, now that the Webley Patriot (Turkish model) has been withdrawn.
Maybe I should test the .22 version with a gas spring — something many have asked for.
B.B.
When you first started this series I wondered about the use of such a cheap scope (~$30) and flimsy mounts on a sledgehammer-of-a-gun like this one. I’m wondering if a stouter scope and/or mounts might have improved things a bit.
While I’m thinking about it – have you ever run into a situation where a gun is ‘scope sensitive’? I’ve recently done some 60-yard testing with most of my springers using a Crosman 3-9×40 with a 1 piece mount and a a 3-9×32 Powerline that I believe is identical to the one in this test.
It really seems that some of the guns that shot poorly with one scope did significantly better with the other. Some preferred the Crosman, some the Powerline.
Or is this probably due to some other variable (like my shooting ability)?
Vince,
Like I hinted in the report, I think this rifle is capable of better groups than I got. And a better scope would certainly help the situation.
As for a rifle being scope-specific, I’ve never encountered that. Or, if I have, I haven’t noticed it.
B.B.
Good morning B.B., Do you think that this rifle would perform better with the heavy .177 pellets like the Eunjins, Samyangs or Predator Big Boys? Possibly you’d share an educated guess on their velocity and energy? Thank you Mr B.
Happy Thanksgiving to one and all!
Hello,
I recently purchased a first variant Crosman 357, the one with a 6-shot cylinder and brown grips. Does someone know if the current 10-shot cylinders for the Crosman 357 will work in a first variant 357?
Thanks.
Six-Shooter.
Vince,
I also thought that my spring air rifle might have grouped better with one scope versus another, but I never was certain and did not pursue this as I was focused on the scope and not this other possible factor. At the time I thought the mount was probably not tight enough and things were moving.
I never noticed this effect on PCP or CO2 guns.
Anything that touches a spring rifle would seem to affect its vibration/harmonics, and so even changing the clamps could make a small difference I suppose.
– Dr. G.
DR. G, I was wondering about an efect like that. But BB has shot a lot more guns than I have, if this was likely to be a significant effect I’d think that he would have seen it. More than likely, I was just shooting better one day than another, although the difference really was quite dramatic.
And no, the scope wasn’t moving in either case. I checked for that.
RE: Scope Sensitivity
Perhaps this is really the difference between a good scope and a poor one?
Does seem that due to vibration that the adjustable part of the scope could shift. Especially if adjusted near an extreme.
Is there really anyway to test to see if the scope has shifted other than to look at the grouping?
Herb
Mr.B.,
I would guess the gun would lose energy with those heavier pellets. That’s been my experience with springers.
B.B.
Six-Shooter,
Not sure which 357 variant I have–but it did come with brown plastic grips. The 10 shot cylinders work just fine.
Derrick
B.B. A follow up question please:
We talk about using the heavier pellets in the PCP’s to keep their velocity below the speed of sound because of accuracy issues–why the difference with the springers?
Why do the springers loose energy with the heavier pellets? Is that because the volume of air that is compressed by their pistons is too little, i.e., dosen’t have enough stored energy, to drive the heavier pellets or is there another reason?
Thanks for your insights, Mr B.
Thanks Derrick. That’s what I was hoping for. 🙂
Mr. B., Nobody really knows the answer to your question.
Sorry.
Anonymous: I think that you an I are missing some law(s) of physics that governs how compressed gasses behave when they are released, but I don’t have a clue what they might be. Just my thoughts though, but thanks for your reply–Mr B.
Mr.B.,
The Cardews did a chapter on spring piston efficiency in their book and I believe they addressed your question. I’ll have to read it to discover what they found.
I know in general springers like lighter pellets better, but I have seen some reversals of that when extra weight was added to the piston, so I’m guessing it has to do with piston bounce. The heavy pellets make the piston bounce more and the lighter pellets get going faster, which translates into greater efficiency.
The reason we use heavy pellets with pneumatics has to do with their longer acceleration time. They can extract more energy from heavy pellets.
B.B.
CO2 + Heater
I was just shooting my CO2 rifle with 31 grain pellets @ 10 yards at avg. of 517 fps = 18 ft./lbs. It was chilly, and so I put the CO2 tank a couple feet from the heater for 10-15 minutes and…
31 grain boosts to 564 fps = 22 ft./lbs.
For some reason, while the 31 grains (a tight fit) move at the above speed, the 26 grain (looser fit) only move at avg. fps 575 = 19 ft./lbs.
– Dr. G.
RE: Heavy Pellets in springers
The assumption is that for the springers the piston reaches the end of its travel before the pellet exits. Then when the piston rebounds it reduces the pressure in the barrel. (The transfer port works both ways!) Thus heavy pellets stay in the barrel longer and thus they aren’t accelerated like lighter pellets which leave barrel more quickly.
Herb
B.B. and Herb: thank you both! Thank explains the why. The piston rebounds increasing the volume of the compressed space which allows the air to expand reducing the energy available to move the heavier pellet. Mr B.
Thank you. I always enjoy your articles. I was wondering at what velocity does rifling in the barrel of a pellet gun really make a difference? Thanks
Interesting question, Anonymous.
I’ve got a .38 cal smoothbore barrel project on the list coming up. Any info on velocity/rifling would be appreciated.
Derrick
BB, yesterday I mentioned that I had gotten a .22 rimfire bullet trap for about what the Daisy pellet trap costs, and you said it was a good deal. I just double-checked the price with that vendor and it got cheaper! The Do-All Bullet Box for .22/.17 rimfire is now in stock and under $35.
Again, I’m assuming that I shouldn’t post the link..
Vince,
Yeah, I gotta ask that you don’t post the link to the Do-All Bullet Box, but at $35 I don’t know how anyone could lose!
B.B.
Rifling,
That’s an unusual way to ask the question – At what velocity does rifling make a difference?
Rifling is there to provide stability to the projectile. And there are many other ways to do the same thing.
I’m not sure how to answer you because I’m not sure I understand what you are asking. There is a relationship between velocity and rifling and the key is the stability of the projectile. But every projectile has a different set of requirements for stability.
A sphere, for example, needs less rotation than a cylinder. And a diabolo pellet that already has high drag has even less need for rotation than a sphere. So there isn’t a single answer to your question.
The answer is – it depends on the projectile.
B.B.
Derrick,
You need to start looking into the Greehill formula that helps calculate the required twist rate for conical projectiles. You will learn that it depends on the length of the projectile.
B.B.
bb first off i do watch the podcasts. secondly after your comment, a switch in my brain flicked, and i had a revelation. in chemistry, i learned about the ideal gas laws. PV=nRT or more usefull for this topic is P=(nRT)/v. if the value of one variable is reduced in an equation like this, the resulting value is also reduced. Therefore when the mass of the air in the tank (n) decreases, so does pressure. My chem teacher would be so proud (unless if i’m wrong). However, i still believe a podcast on this topic would be a good idea. One question is whether or not the talon ss would retain its accuracy capabilities when using CO2
thank you
john from jersey
Jersey John,
Thanks for getting back to me! I will do the first report bin the podcast for you. It will be taped this weekend.
B.B.
I woulda figured that a sphere would be the shape that was least in need of spin-stabilization. A high-drag diabolo pellet can still tumple and ‘keyhole’, and if the pellet starts going sideways during flight its trajectory gets unpredictable. But if a round ball tumbles in flight, well, aerodynamically it really isn’t going to make much of a difference.
Vince,
You’re right, of course. A perfect sphere is inherently stable. The trouble is, many bullets (balls) are not perfect spheres.
Where the pellet has high drag for stability like a dart, a ball acts more like — well, a ball. It will curve, dip and even try to climb, based on what happened to it last.
B.B.
Hi BB, can you please answe my question about crows? I would like to know if a 397 with premier hollow points or kodiaks on 8 pumps, directly at the kill zone, can humanely take down a crow? the distance is 10 yds- 15yds (yes, i can get that close.)
Hi b.b.
Cowboy StarDad, OT as usual.
Well, it seems everytime I’ve decided that I’ve found the perfect Christmas present (a realistic pistol with more accuracy than the PPK, which I love), I’m thrown a curve.
So I know I want to stay with the Umarex products. You seem to think highly of them plus so far (maybe 500 shots) the PPK has worked flawlessly.
So…CP88B, Desert Eagle, Beretta BM92B or the Colt 1911 A1.
They range $175 to just a tad over $200.
Are any more accurate than the others?
More dependable?
Which would you choose.
Hi Jersey John: My Talon SS doesn’t care CO2 or HPA, tiny little groups either way. A change in POI perhaps, depending on the power wheel setting. I enjoy the CO2 for paper punching, plinking, and pest control. I’m more than satisfied with it. Mr B.
Vince: Would you send me an e-mail about the pellet trap? Dropdog2@Aol.com Thanks Mr B.
STP,
Yes, with one of those two pellets at that range and with 8 pumps I’d say the 397 can do it.
B.B.
Cowboy star dad,
All those pistols SHOULD have equal accuracy, but when I shoot them the 1911 does measurably better than the rest. It can shoot one-inch groups at 10 yards, while the others, except for the Desert Eagle, are 1-1/8" guns.
The Desert Eagle is a strange gun. It shouldn't be as accurate as the 1911 because it has blowback, but as I recall, it does shoot just as well. And with blowback, you are always shooting single action, so the trigger is nicer.
However, there is a gun that's even better. The S&W 586 is both more accurate and has a better double action trigger pull than any of the Umarex pistols. I would get the 6-inch barrel.
As for dependability, I'm not a good judge. Umarex guns seem to last forever for me, yet I read all those reports about the guns that fail. I don't know what to say. From my own experience, all Umarex pistols are equally dependable.
B.B.
mr b, are you able to keep tight groups out to 50 yards with CO2?
John
thanks, b.b., I'll be ordering the Colt tomorrow.
I appreciate your input on the S&W. Unfortunatley I look on revolvers the same way I do minivans…a necessary evil 😉
(problem is I drive a Toyota minivan…which was preceded by an Alfa Romeo Spider.
Sigh……..)
CowBoy StarDad
Cowboy Star Dad,
Yeah, we have a Toyota minivan, too. It’s hard to complain when the thing is so darn reliable.
B.B.
I’m always fascinated when we challenge the laws of physics –
Some observations:
1. On Springers losing energy with heavy pellets: The energy of a springer is the energy you put into the spring when you cock it. The spring releases the energy when you pull the trigger. The game is to get as much of this energy as possible into the pellet, (the rest escapes as heat and moving air) A heavy pellet has a slower acceleration, hence higher dwell-time in the barrel, and more time to absorb more energy. In reality, piston bounce is the rifle (actually, the compressed air), putting some of that energy BACK INTO the spring. If the pellet leaves the barrel before the piston can “re-release” it, then it is lost – the pellet can’t capture it.
2. Whoever tried using the gas laws is correct. Any reduction of air-mass in a pressurized vessel results in less pressure. It also results in lower temperature, (same formula). CO2 guns have the temperature problem, but not the loss-of-mass problem. CO2 cartridges use liquid CO2. As each shot is fired, more liquid converts to a gas, and the pressure remains constant as long as time is allowed for the temperature to equilibrate. (so, the Talon should do even better on CO2, but will probably suffer from lack of energy, assuming it was designed for higher pressures.)
3 Finally – “sphere inherently stable….” only if you can get it moving without spinning in any direction, (which is near impossible). Once it’s spinning, there are going to be pressure differentials that are going to cause it to move off a linear path.
b.b…where I live the Toyota’s aren’t that common.
Mine is an older one, a ’98 Previa that I love because of its rear-wheel drive (I spent a lot of years in the past behind the wheel of a Lotus Escort competition rally car and much prefer rear-wheel drive to front), and because at 260000mi it seems to be just nicely broken in.
And for ferrying the boys around or hauling camping gear it just can’t be beat.
But oh for those sunny days with the top down on my Alfa.
But with guns I don’t worry about practicality. I know that revolvers are inheirently more accurate and more trouble free than revolvers…but there’s just something so damn sexy about a big-assed auto.
Cowboy StarDad
Regarding spinning projectiles, an elongated projectile like a bullet or pellet, is much more likely to spin on the long axis than any other, whereas the sphere, as a symmetrical object, can spin in any direction. This might be related to the differences in “stability.”
On the subject of rifling, I suppose there is an ideal case where a projectile is going so slowly, like 2 mph, where the spinning effect is insignificant. However, I expect that for any velocity of interest to shooters, like 350 fps and up, the spinning will only help and will probably keep getting more important as the velocity goes up although that is just a guess. I think it is also important to distinguish between the velocity of the projectile and the twist rate of the rifling which amounts to the rotational velocity as the projectile spins around its axis. Amongst all the variables, the only landmark that I have identified is the ideal case where you have the heaviest projectile that you can spin without overstabilizing it. Things seem to go downhill once you get away from this configuration for various reasons. And this applies only to firearm bullets. The Diablo pellet with its design would be different.
I feel bound to review a new product. I suppose that not many people go airgunning in the rain, but for those who are out for some other reason, you might have use for the Cabela’s rain jacket that I just bought. I had my first chance to test it in a steady rain, and not only was it completely dry on the inside, but it was dry on the outside as well except for a small amount of beading. There was no absorption at all. Maybe this is old news to you outdoorsmen, but I’ve never seen anything like this. Rainy weather is now like nothing at all. I’m afraid that I can’t find any model specifications on the jacket, but I’m sure that the folks at Cabela’s could help.
Cowboy Dad, my CP99 Sport from Umarex has performed like a champ from the first day except for the trigger sticking very occasionally.
Matt61
Jane,
Thank you.
B.B.
Cowboy Star Dad,
Well, you know my feelings about the 1911. I love it. And I know revolvers are better in all ways, too. But I still love the 1911.
B.B.
Hi Jane Hanson: Welcome back and thanks for your imput. The Talon SS has a different valve for CO2. With a power wheel setting of 5 I don’t see any difference in POI at 20 yards between CO2 and HPA. However, I haven’t gotten around to putting them on the chronny to really tell. By the way which air rifle did you finally decide on? Happy Thanksgiving Mr B.
B.B.
You’ve got one of the best blogs going. Sometimes I’m just too busy to connect. Is there a chance I missed the review of the Career Infinity you were going to do?
Jane
Mr. B.
I’ve yet to decide. I am impressed with the AR6, but also sense that Wayne would take an AA410 above anything. Still, on paper, the Career Infinity should have more stopping power than the AA, and more accuracy than the AR6.Only after BB tests it, will I have anything tangible to go on. Not much user input to be found.
I hoping to buy something soon – the groundhogs are making a mess, (getting ready to hibernate I guess).
I also see that Evanix has released a new model – “Blizzard” but it looks to be just a side-lever variant of the AR6.
Always looking for input…
FJane
B.B.
Revolvers better in all ways than a 1911? What about accuracy, trigger pull, and magazine capacity?
I’m trying to get a handle on the gyroscopic effect of wind on bullets. As I understand it, a crosswind from the left on a bullet with a right-hand twist should make it go up; a wind from the right should make it go down. Is that right? I’m basing this on the way the wind adds or subtracts from the air flowing around the spinning bullet.
Matt61
FJane: I am a blued steel and hand rubbed oil finshed walnut kina guy, but I’ve become as big a fan of my Talon SS as Wayne is of his S410. Check out B.B.’s reviews along with Paul’s videos. There are after market bloop tubes that really do work, if that is a consideration for you. Just a suggestion for you to consider. Mr B.
B.B.–Scott298, Just wanted to take a minute and wish you and your wife a verry happy Thanksgiving-hope to be writting to you before xmas and I hope all is well-Scott Herlihy aka Scott298
Mr. B.
I appreciate the suggestion. I just can't get into a Talon. I'm sure it's great, but it's just not me. I wear gloves in the cold, and changing clips is a whole lot easier than one pellet at a time. Besides – I'm with you, the feel of a nice wooden stock is an essential part of the experience.
Thanks & regards,
Jane
Help me, but as a scientist, I can't resist:
Spinning projectiles are sublect to two major effects, (among many).
One is the "Magnus effect". A spinning object creates a whirlpool of fluid, (air) around itself, and experiences a force perpendicular to the line of motion and away from the direction of spin. We need to worry about this shooting into a cross-wind, and yes, a wind from the right will alter the normal drop of the pellet, (not likely it will actually rise – but is will certainly drop faster if the wind os from the right). Round-ball shooters need to worry about Magnus effect, because the balls will always have some sort of back or forward spin.
The other effect, the gyroscopic effect, is the one BB speaks of when rifling imparts spin stability. This is based on conservation of angular momentum, but someone already mention the Greenhill formula, for determining proper spin & speed.
By the way, as a handgun nut, I say revolvers win on reliability, but a good autoloader beats'em for everything else.
best regards,
Jane
Jane,
You’re spot on in my opinion about handguns. Reliability is number one priority and a revolver wins hands down. After all, all a handgun is for is to fight your way back to where you left your rifle.
Jane, I’m falling in love with you. Unfortunately, I don’t think our conversations would last more than a minute since I couldn’t keep up. Really appreciate your “rocket scientist” perspective on this blog.
kevin
Jane,
Thanks for the clarification. The Magnus Effect is what I was thinking about. The blog had a conversation some time ago about spin stabilization and its various effects, and I think we came to the conclusion that it’s complicated….
All, regarding handguns, I expect that the generalization about revolver reliability is probably true, but I would love to see a match-up between a revolver and the famous Glock with its 60,000 round endurance tests. I’ve been curious why the Glock is so reliable. Surely the polymer can’t make that much of a difference. Does the fewer number of moving parts represent some kind of design breakthrough?
Matt61
Jane,
Back from a journey to Portland.
I just traded a SW autoloader .22, that only shot LR, for a HR .22 long barrel revolver, so I could put shorts and CCI for more quite shooting and “walking the can” as Volvo says..
You know the Air Arms S410 in .22 has a lot of power and accuracy as well, I just got one without a power adjuster, and it does have a valve lock issue, but not too bad. It’s getting more than 70 shots on a 2,975 PSI fill… and at that fill level the valve lock is very min… 73 shots with JSB 15.9 exacts, starting at 845fps peaking at 1009 and the 73rd shot at 840fps. and the 100th shot at 616fps… Kodiaks 21 gr are the most accurate in it.
And my older AA S310 .22, 10 shot mag. with beech stock, (which I’m selling now that I’ve got the walnut stock 410) is almost as good in number of shots… but, I haven’t tested it as much, so I can’t give details as yet.
here’s a link on my AAs410 that I just traded for on yellow:
http://www.network54.com/Forum/79574/message/1221266159/Air+Arms+AAs410+10-shot+.22+with+incredible+walnut+stock.+41+FPE+with+Eun+Jins!
Wayne,
Ashland, Air Rifle Range
.22 Multi,
RE: AR2079A easier to convert. Thanks for the suggestion; that is something like what I thought I could do at one point, but I got some bad feedback on the 79 series (problems with leaks apparently). Also, I like the full forearm of the 78’s. There are several people online who seem to have converted 78’s to unregulated HPA just by using a different bulk fill cap, as well. Any ideas are welcome — I have no idea what I’m doing:).
Matt,
I understand your excitement over the coat. My wife got tired of my embarassing technicolor duct tape raincoat and got me a nice, hooded, ligthly insulated coat for working outside. It makes a world of difference: with mid 30’s and pouring rain, feels like I’m sitting in my living room. So far its been good down to 16 degrees as well, but I run hot.
BB,
I am interested in AA S200, but not committed to buying one. I was hoping to stay in the Discovery + pump range, although it may be some time before my skills justify/demand a rifle upgrade.
Wayne – I knew you were out there – I can appreciate the AA410. You prefer it to the AR6? Might the Career pack a bigger punch? I’m dying for BBs review.
I can see your point on revolvers – everyone has a different “fun factor”.
Kevin – great comment on the reliability – “fighting your way back to your rifle”, I can use that. I’ve had a bit too much wine – so my spelling is off, and so is my Magnus effect: wind from the left, the pellet will drop slower – or hit high, wind from the right, it will drop faster and hit low.
The Glock doesn’t really carry a reputation for reliability in most circles – the honors typically fall to Berreta and Sig. (The US military thinks so, also). Blackwater, probably the largest private armed force on the planet, (and one that doesn’t buy “low bid”), uses nothing but Sig 226.
Curiously, no one ever even mentions the reliability of a Browning Hi-Power; kind of like questioning the reliability of a Rolls Royce when you’re talking Chevies and Fords.
It’s late..
Jane
Jane,
With the Korean guns you get a little more power, but not as many shots per fill…. And on the yellow I hear people complain about seals leaking after not too long.. Someone wants to trade me a Career long barrel, double tank, he had to put new seals in it), for one of my Discoveries with a mod and scope…. I might trade and see what they are like…
Wayne,
AARR&R
BG_Farmer,
I can understand wanting the full forearm. I wouldn’t recommend putting higher pressure in the CO2 tube however. It is only designed for CO2 working pressures. Remember BB’s warning (the section labeled “A case in point” at /blog/2008/11/hand-pumps-of-antiquity-part-2/)?
You might be able to use a Benjamin Discovery tube with the ’78, but I don’t know if it would have to be modified.
.22 multi-shot
G’day BB
Just got a Caldwell Lead Sled which holds the whole rifle for sighting in. Your frequent references to “holding technique” really amazed me with this device. You can change point of impact so easily I could not believe it! Cuts human failings to a minimum
I normally just shoot standing with my left hand holding something and rifle fore end resting on top of my wrist. Hitting bottle top size targets at 25 yards is about all I need. Using this Sled I could vary groups from one hole to scatter gun groups.
Hell, finger tip versus first joint for trigger ½” group to right, firm hold versus loose hold and you swear you had two different air rifles one expensive and the other a $25
throwaway.
Quite an eye opener!
Cheers Bob
RE: Greenhill Formula
The Greenhill Formula might be a starting point, but it doesn’t seem that bullets and diablo pellets would follow exactly the same relationship. Pellets have a much higher drag.
I suspect that the pellet is very dependent on the center of gravity being appropriately forward. I was amazed that the group size for Beeman Lasers tightened very greatly when changing from 4 to 10 pumps with my Daisy 22SG. The Mendoza Super Diabolo Hollow Point pellets have the skirt entirely filled with lead and are short. I think that they would need to spin a lot faster than is typical to stabilize.
I bought a cheap smooth bore multi-pump and was really surprised how well it shot pellets. It was flinging lead at 10 meters much better than I can do with my Crosman G1 springer. Ouch!
Seems though that pellets are missing one factor entirely. I wonder if you could make a rifled pellet, like the rifled slug for a shotgun.
I have noticed fluting on some skirts, like RWS Superdome. I assume that the fluting increases turbulence which decreases drag. Exactly like dimples on a golf ball.
Herb
Sorry, but I’m going to beat the spin thing some more….
This also is coupled with the shape of the head of the pellet. I seem to remember BB saying that he didn’t think the pointed pellets were as precise because the points wasn’t perfectly centered. Domed pellets seemed to him more forgiving in this regard. (Sorry if I put words in your mouth B.B. …) Wad cutters are very dependent on the flat being perfectly perpendicular and the edges being unmarred.
I assume that the various hollow point pellets have accuracy problems because they are not absolutely radially symmetric. The flared front of the RWS Super H pellets seems a lot more delicate than the Beeman Crow Magnum design.
Overall the point is that head shape seems to be very important in pellets too. As I said, my smooth bore pump shoots better than my rifled G1 springer. I know the G1 isn’t a world class springer, but I did pay three times more for it.
Have a Happy Turkey day!
Herb
Magnus and Gyro effects are distinct phenomena. When you start talking drag, turbulence, and shape, you leave those effects and enter aerodynamics – a whole new set of problems.
Jane,
You haven’t missed the Career Infinity. It begins next week.
B.B.
Scott298,
Mom and I both extend our wishes for a Happy Thanksgiving to you and your family.
B.B.
BG_Farmer,
When I took the idea for the Benjamin Discovery to Crosman, I used the Air Arms S200 as the point of comparison. I told Crosman they had to get the price of their new rifle and pump under the price of the S200 or the whole deal was a waste of time.
My goal for the package was $250, but as we developed it, the price kept climbing. I was the one who put the kibosh on the shrouded barrel and adjustable trigger. Crosman wanted to put it on the gun, but it drove the final price too high.
However, they snuck the manometer and the micon air filter in on me, and I’m glad they did. Those two features really made sense in the final product.
And, by the way, I wish you could hear the talk at Crosman today. They are firmly wedded to 2,000 psi. The fully understand and appreciate the advantage it gives them in the marketplace. Look for the next gun to be very quiet and a 2,000 psi gun.
B.B.
G’day Bob,
That Caldwell Lead Sled sounds like a heck of good testing apparatus! And now you can see the huge effect of a small change in the hold. Good on you, mate!
B.B.
Herb,
The Greenhill formula IS just a starting point. And you’re right that diabolos have different flight characteristics than conical bullets. But we do need to have a starting point.
B.B.
Jane,
From what the guy who wants to trade me the Sumatra 2500 long, with double fill tanks, (checked my notes, not a Career) for the Discovery with mod and scope, said, the accuracy of the Korean guns is good, but not as good as a AAs410, FX, or BSA….. A little more power, slightly less accurate and a lot less shots per fill, and a whole lot louder!!…. just his opinion… I haven’t shot them yet, just the AR6…
Wayne,
Ashland Air Rifle Range
Hi John: I’ve been shooting in my back yard and 20 yards is all I’ve got to work with for now. Mr B.
Jane,
RE: Magnus and Gyro effects and aerodynamics
Aren’t the Magnus and Gyro effects categories of aerodynamic phenomena too? Neither would exist in a vacuum…
That’s the whole point of some of this discussion. A lot of things can be simplified by considering a single factor which is the primary cause (variable) of the phenomena being studied. I’d suggest that the skirt and center of gravity are such factors for the diablo design.
I’m not sure that the Greenhill Formula even applies. Think of the following as a progression of aerodynamic designs
(1) ball
(2) “pill” – cylinder with hemispherical tip and base
(3) bullet – cylinder with hemispherical tip and flat base
(4) mini-ball – cylinder with round tip and hollow base
(5) diablo pellet
(6) Dart
The Greenhill Formula doesn’t predict anything useful for a ball or an dart. Why should it predict anything useful for a diablo? (Granted there is a great gap in the soundness of the proposed design sequence…)
It would seem to me that the diablo design would need a much more sophisticated equation which took into account drag, rotation, and precession. In order to do that you’d have to have some measure of various center of gravity measures.
Herb
Herb,
The gyroscopic effect is not an aerodynamic effect. As Jane stated, it “is based on conservation of angular momentum.” A gyroscope will work in a vacuum.
.22 multi-shot
No doubt I’m trying to split hairs, but there is a difference to me between the angular momentum of a gyroscope, and the “gyroscopic effect.”
The nature of the “effect” is to use the intrinsic angular momentum of the projectile to stabilize the projectile against something else. If I were to “fire” (gun slingshot whatever…) a projectile in outer space, the shape of the projectile wouldn’t matter. It wouldn’t matter if it were spinning. The projectile would follow a simple ballistic path.
The angular momentum of a projectile does “average out” slight mass differences which would be influenced by gravity. But my contention is that much more importantly the angular momentum of a projectile averages out radial aerodynamic imperfections (like a tiny nick in the dome of a pellet). Thus the greater the aerodynamic imperfections, the faster the projectile has to spin to average them out.
Herb
Ugh…
The angular momentum doesn’t average out the radial aerodynamic imperfections, it stabilizes the projectile against them. In essence the aerodynamic imperfection would take longer to move the projectile noticeably off its path, than the projectile is spinning. So the projectile appears to be on a constant course.
Herb
off topic but three questions for bb
1 favorite gun pcp,spring,anything
2 are going to due a review on a crosman quest 1000x if not what is your take on it
3 can i use a regular compressor to fill up a pcp.
Auston,
1 My favorite airgun changes with time. But a lot of the time it’s a Talon SS.
No, I don’t plan to review the Crosman Quest 1000X. I know almost nothing about it, so let’s hear from some of our readers who own them.
A regular air compressor only goes up to about 175 psi. You need to get to 3,000 psi. I paid $1,600 for a compressor that goes that high.
B.B.