by B.B. Pelletier
Part 1
Part 2
Part 3
Part 4
Part 5
For the benefit of readers who have landed on this article first, this is the sixth test in a series of reports designed to test how velocity affects accuracy. I’m using a Whiscombe JW75 breakbarrel/underlever rifle with a .177-caliber barrel installed. That way the same powerplant is being used for each test. I’m controlling the power of the gun by the use of different air transfer port limiter screws that allow less and less air to past through.
The Whiscombe rifle uses dual opposed pistons that come together to compress the air when the gun is fired. The rifle has no recoil and just a minor impulse that can be felt — yet it’s one of the most powerful spring-piston air rifles ever made. My rifle can produce over 30 foot-pounds in .25 caliber.
Four pellets were chosen at the start of this test and have been used in each velocity and accuracy test that’s been conducted. Two of them were supersonic in the first test and one remained supersonic in test two, while the other was still in the transonic region where wind buffeting occurs. It’s testing exactly what it was designed to.
Today, I installed a smaller transfer port limiter to slow down the four test pellets even more. This was the first time all four pellets were safely below the sound barrier, and the shooting was uniformly quiet. You probably should read the first five reports at the links provided above to understand all that’s happening.
Beeman Devastators
This 7.1-grain lead hollowpoint hunting pellet has been the biggest surprise of this entire series. Normally, these types of special pellets are designed for maximum mushrooming and are not that accurate — at least not in my experience. But the Beeman Devastator has proven to be the exception. From the start, when it was leaving the muzzle at an average 1,216 f.p.s., it was accurate. So far, we’ve conducted only two accuracy tests, so the results of this one should prove interesting. As I said, this was the first time this pellet has left the muzzle at subsonic speed.
The average velocity was 973 f.p.s., with a low of 967 and a high of 977. That’s only a 10 foot-second difference between the slowest and fastest pellet, which I think is amazing. Usually, a pellet this light will also have a much larger total velocity spread over a 10-shot string. At the average velocity, this pellet is cranking out 14.93 foot-pounds of energy at the muzzle. That’s down from the initial 23.32 foot-pounds it was making when there was no transfer port limiter in the gun.
Can you guess what this pellet will do in the accuracy test? I think it’ll be even more accurate than in the past. But who knows?
Crosman Premier lites
Crosman Premier lites were next. Initially, they were leaving the muzzle at 1,134 f.p.s. when there was no transfer port limiter in the gun. Today, they averaged 915 f.p.s. and the spread went from 911 to 919, for a super-tight 8 foot-second difference. At the average velocity, these pellets were producing 14.69 foot-pounds at the muzzle.
Any guesses as to what this pellet will do in the accuracy test? The difference between the first and second accuracy tests was very small, but we’ve finally gotten the velocity down out of the transonic region, where all the buffeting is. They didn’t break the sound barrier the last time; but at an average 1,057 f.p.s., they were well into the transonic range. There could be a happy surprise from the Premiers.
Beeman Kodiaks
Beeman Kodiaks averaged 819 f.p.s. with this transfer port limiter. The spread went from 817 to 824 for just a seven foot-second total variation across 10 shots. The muzzle energy was 15.2 foot-pounds. Notice that this heavy pellet is producing more energy than the two pellets that are lighter — something that’s not supposed to happen with a spring-opiston system.
I need to interject a word on Kodiaks. For some reason, their weights have varied widely over the past couple years. Where they had weighed 10.6 grains for several decades, someone decided to reduce the weight to 10.2 grains in 2010. Those are the pellets I have. But now I notice that the weight is back up to 10.4 grains. Obviously, someone is adjusting the weight of this pellet that was once considered one of the three most accurate .177 pellets on the market.
Kodiaks have been the most accurate pellets in both the previous accuracy tests (after I started using the scope level), but I don’t know if they’ll continue that trend at this new lower velocity.
Eun Jin domes
The 16.1-grain Eun Jin dome is really too heavy for the Whiscombe in its most powerful form. Certainly as the power is reduced, they become even less appropriate. In this test they averaged 618 f.p.s., and the spread went from 615 to 624, for an 11 foot-second total. At the average velocity, these super-heavyweights are producing 13.7 foot-pounds at the muzzle.
They produced the worst group last time, opening up from the group they had made with no transfer port limiter installed; and I predict this trend will continue in the next accuracy test. These are really best in powerful PCP guns — not in spring-piston guns.
What’s next?
Next, I’ll test the accuracy of these four pellets at 25 yards. I’ll use the same careful technique that I’ve been using so far to keep the results as free from bias as possible, so this should give us a good look at how velocity really affects accuracy — at least with these four pellets in this one gun.
You may not remember this, but at the beginning of this series I said that if the results of three velocity and accuracy tests seemed to warrant it, I could do a fourth test with the velocities cranked down very low. I’ll hold off on the decision to do that until I see the results of the next accuracy test.
Whether I do a fourth velocity/accuracy test or not, I’ll write a final summary report on all that’s been done in this test. If it seems worthwhile, I could do a second test using a Talon SS, so we can see the same relationship in a PCP gun. However, that hasn’t been decided, yet. We still have to get through this one.
Seems strange to ask question that aren’t related to blog entry but since that appears to be the case here. Plus I tried to make this comment late on yesterday’s blog and never saw it so going to try again. Hope it doesn’t end up double posting.
I have an old RWS 36 that I still enjoy shooting but have a problem sighting it in. Presently I am shooting Crosman Premier hollow points and using the iron sights that came on the rifle. The rear sight is cranked all the way down. The rifle groups well but shoots about 2 inches high at 10 meters and 4 inches at 20.
I shoot empty shotgun hulls at 20 yard by sitting them on a standard vegetable can and aiming at the bottom of the can. This happens regardless of the pellets used so far but haven’t tried any of the extra heavy pellets.
I know I can bring the impact point of a handgun down by going to lighter bullet, faster loads but have no idea if this would work with a spring piston air gun. Any idea of what might be wrong or solutions.
I’ve also thought about getting a Mendoza Diopter 11mm Dovetail sight. Would this give me the needed additional adjustment range?
Bill,
The Mendoza peep sight will exacerbate your problem! You need to raise the front sight. It sounds like the barrel is bent up from someone pulling the trigger when the barrel is open. One time is all it takes. Sight along the outside of the barrel and see if it slopes up.
B.B.
I’ll check it out today. If it is bent what would be the best way to try and straighten it, or is that just wishful thinking.
Bill
Yes, you can bend the barrel back. I have never done it, but maybe BB, Vincent, Nick, or Derrick can pipe in. Between the four of them, I think they know all there is to know about airguns..
Bill,
Yes, it can be straightened. First let’s see if it is bent and we’ll proceed from there.
B.B.
Bill,
As BB said, let’s confirm the barrel is bent and that is your problem before doing anything else.
when BB chimes in, he really is the authority on all things airguns and we all highly respect him. Here’s a blog he wrote back in 2008 on the subject:
/blog/2008/7/straightening-barrels/
Again, that bent barrel may not be your culprit so check everything carefully.
Fred PRoNJ
Can’t see any bends on the barrel. I laid a straight edge along sides of the barrel, used a .17 cleaning rod, and finally looked down the boar with a strong light shinning in. Could detect no unusual shadows, irregular rings of light or anything else that might indicate a bend.
Since the rifle still groups nicely I don’t know. Any ideas on raising the front sight? It is a thin metal blade insert in the globe.
Bill,
The easiest way to raise the front sight is by gluing a thin metal post to the back side of the front sight post. Start by raising it by 1/8-inch and see what that does. Use non-permanent glue until you know how high it has to go.
A neater way of doing it is to make a shim to raise the entire front sight base. If it’s an old 36 you should be able to do that.
B.B.
Thanks, I try the glue on routine. I had thought about a piece of shrink tubing but don’t have one that will shrink down small enough.Would love to shim but he dove tail the globe goes into is so shallow I don’t think I’d gain more than 1/64″ if that.
What is puzzling is this started over night. Also had a shift in windage but not that great.
Bill,
AH HAA!
Your next to last sentence provides a great clue.
Vince, are you following this discussion?
Bill, I want you to do something for me. I know you probably don’t own a chronograph, so can you shoot a pellet into a soft pine board and tell me how deep it goes? Wear eye protection when you do it and prepare for penetration of at least one inch. I don’t think it will go in that far, but you tell me.
B.B.
I do have a chrono and will do so tomorrow, raining here now. I chronographed it a few weeks ago along with some other guns. It was getting a 10 shot average of just below 850 fps with 7.7 gr. Gamo pellets. This is very close to what I got when I chronographed it a few years ago. FWIW, it still puts the premier hollow points through both sides of a standard non aluminum vegetable can. BTW, it shoots high using the premier, gamo hunters, and Beeman Laser so it just isn’t the pellet. I do wonder if premier 10.5 gr. heavy pellets will help.
Bil,
Those velocity numbers will tell us the health of the action. They are important.
B.B.
Looked like I hi the end of the reply allotment so had to drop back to have a reply link.
I shot 10 Crosman Premier pellets across my screens this AM. Avg velocity 771.1, stdev 15.0 and spread was 48.8, which seems a bit large. If I threw out the slowest 3 shots the spread would have been about 20.
This is a bit slower than I remember but when I chronographed last time I was doing several different guns. Dummy me didn’t save the results so I can’t look back. The energy came out to 10.4, which does seem to be a bit lower. Seems like I got 10.9 last time, but that was a different pellet and I don’t have any more of the other pellet to test.
Did you oil the piston/seal just before the problem started?
Good idea but no. I only use chamber oil maybe every 2500 or so shots. I’m about half way into the interval.
Just an aside:
The lower point of impact for handguns when using a lighter/faster cartridge is commonly attributed to the bullet leaving the barrel sooner — before recoil has rotated the muzzle upwards.
Since spring piston airguns have an atypical recoil pattern (a small rear thrust at the start of the firing cycle followed by a /foreward/ jump when the piston bottoms out), and the mass of the airgun is so much greater than the pellet, I doubt going lighter would help… More likely, the flatter trajectory will /raise/ the point of impact relative to the sight-line.
Bill, you checked the barrel for straightness, but did you check to see if it’s parallel to the spring tube? Is there any chance it’s pointing upwards when locked up?
Your most recent chrono test… was that before or after this problem started?
Can any one give exact difference of weight between a beech stock Air Arms Pro-Sport and a walnut stock Air Arms Pro-Sport?
thanks
Anon,
Rough and dirty the difference will be from 2 to 6 ounces with walnut being heavier than beech. Not gonna make or break the deal either way unless you want exceptional figure, then walnut is the only way to go.
No one can give an exact figure, because the density of wood varies from one plank to the next.
B.B.
Anonymous regarding weight of AA Pro Sport,
Pyramyd AIR weighs the guns in order to give you their specifications. BTW-only retailer that I know of that does this in most cases. On the PA website it shows the walnut version weighs 9.03 lbs and the beech version weighs 8.6 lbs.
kevin
The quick answer is “No”.
The extended version is pieces of the same wood will vary in density, thus varying mass. Two identical rifle stocks of the same wood will have a different mass. Walnut is a denser wood than beech so of two identical stocks, walnut will indeed have more mass than beech, but in the case of your question the difference is likely at most a couple of ounces.
If you simply must have a number, pick two.
BB,
Regarding the Premiers, are you sure you’re out of the transonic region? Normally it’s 0.8 to 1.2 x speed of sound. Using 1126 ft/sec. for the speed of sound (varies with temp., etc), 900 ft/sec. is the threshold. So, while the buffeting may be reduced, I don’t think they are at optimal velocity yet. This is a long way of saying that even if they show better accuracy, I would go down another 50 fps in velocity so that they are all clear of transonic region. It might take two steps to get the Devastators under the threshold, which would be pretty interesting, since they appear to have magical properties in the transonic region (aerospike as someone suggested?), and that begs the question as to how they work outside the transonic region.
BG_Farmer,
What you are really saying is that you want a fourth test.
B.B.
That’s it, if you are so inclined — it sounded like you were thinking of wrapping it up, but I think there is still interesting stuff to see. Even, if there isn’t, we’ll know more than we do now, but I’m almost willing to bet the CPL’s will improve down to about 850 or 875.
By the way, I don’t know how my comment got there (as a reply to RR), sorry.
B.B.,
Re: Fourth test
You searched for a reason to shoot this Whiscombe and have found a good one. Tired of shooting the Whiscombe?
Seems to me that it’s tough moving forward since discerning a change in accuracy is measuring group sizes to a hundreth now. Nonetheless, I agree with BG Farmer in that I think the cpl’s and devastators are still being shot too fast.
kevin
Kevin,
I don’t mind doing the fourth test. I just don’t want this series to bore too many readers. I remember getting carried away with the FWB 124 and I don’t want that to happen here.
B.B.
Understood.
Maybe you should continue the test until the Whiscombe can shoot a group as well as your R8 and then call it done. 😉
Kevin,
😉
B.B.
BB
I don’t recall you getting carried away with the 124. What I recall is you giving a quintessential airgun the respect and attention it deserves. I would own one, except for the fact that the prices usually surpass what I am willing to spend. I screwed myself out of one recently by hesitating. Just as well, I need a bigger house anyway, to store more airguns.
Carried away? What’s that??
Hi, B.B. I think you might be overestimating your capacity for boring us. This is a very fun topic. I for one am far from bored, and would rather see you flirting with “carried away” than stopping short. I say you take it as far as you like, including the PCP-based follow up with the Talon. Especially if you’re enjoying yourself!
Thanks,
Jan
BB,
C’mon man, you know this is the stuff we’ve been reading and learning from. There’s nothing wrong with an in depth, 6 part series that gets really detailed when it’s not the norm. This blog has a following that appreciates the amount of work it takes for a thorough review and no one here is shunning the nubee either, or any review geared that way. Don’t get soft on us now! If you got something, let’s have it! Even the nubee can’t stay away from your blog when it’s over their head, they just scramble to catch up like I did.
ka
ps, I love it when I can chose the ‘ignore’ selection with spell check!!
B.B.
Another broken rule? More energy from a heavier pellet in a springer? Not a big surprise from what I have seen, although I am not looking at pellets that heavy.
With my 97K and .177 R9 , I find that there are pellets that are both heavier and lighter than the one that produces the most K.E.
The .22 R9 REALLY likes to break rules with different pellets.
Between 16 gr Exacts, CP, and Superdomes, Exacts are slowest, Superdomes fastest, and CP in between.
Yesterday I got in 8 more kinds of pellets to try. More surprises. None of them were “drop in” loose, none extremely tight.
I saw some really strange velocity ranges that were completely unexpected. It shot anywhere between 600 and 750 fps depending on which pellet was used. I shot a few of each to see what the chrono could tell me, and found each to be pretty consistent. These pellets were ALL lighter than the 16 gr Exacts (630 fps). I did not run any K.E. figures, but it is obvious to me that when a rifle shoots a heavier pellet faster than a lighter one that the heavier one has more energy.
This rifle does not care about ANYBODY’S rules.
twotalon
B ill,
I had the same problem with a FWB 124 I had bought earlier this year. As you are using the sight that came with the rifle, I would check to make sure it’s not loose. Make sure the mounting screws are tight to the action. Then check that the stock screws are tight, including the trigger stock screw. Finally, if you bought this rifle used, someone may have dry fired it and bent the barrel upwards. There are a number of ways to check the upwards bend of a barrel, from visually checking to using a level or even two or a long straightedge. In my case, the sight that came with the FWB was not properly mounted in the dove tails due to interference with the stock. I solved my problem by switching sights to a Williams sight with a blade rather than a peep but even that was being pushed up by the stock so I went with an aperture sight that fits only in the dovetails and doesn’t hang down to the stock.
Good Luck.
Fred PRoNJ
Fred, You know, you can always cut a little out of the stock for the sights to fit. ;o
BB, I for one would like to see what the Talon SS does in a test like this. If you’re willing to spend the time it takes, it is a lot of work. For that matter, maybe I will do my own test with my Crosman 760. Pellet velocity vs. throwing stones!
It would be interesting to see what the deal is with the changing of the weight on the Kodiaks.
ka
KA,
I had suggested I was going to do that on the Blog and immediately got flamed by numerous bloggers. The message was, “DO NOT TOUCH THAT STOCK ON THAT FWB 124!”. Kevin L came through with an aperture sight that was an option for the 124 and that works perfectly. While the blog might look the other way if one alters a stock on a Gamo or Crosman, it appears to suggest one is going to put Dremel to stock on this rifle is easily up there with original sin (joking all).
Fred PRoNJ
I know, I was foolin’ with ya.
ka
Anyone looking for an R8?
http://www.airguns.net/classifieds/show_ad.php?adNum=38265&adSort=&StartingAd=0&NumberOfPages=5
BB
I think this test should definitely also be duplicated with the Talon SS, for comparison. This is because the Whiscombe is kind of a strange bird, to say the least. It has features that would nearly negate any kind of reliable comparison to any springer most of us will ever be able to own. However, these same features mesh nicely with what a PCP is capable of. This would be kind of a 12 o’clock showdown between what fine springers and fine PCP rifles are capable of. Sorry to end a sentence with a preposition.
Maybe we could use a quick summary of the findings of the pellet vs. accuracy test. Between the different pellets, I’m getting a little lost.
B.B. and Kevin, thanks for the info about the Tyrolean stock. If that design gives you problems with an airgun, it would probably really rattle your teeth on a firearm. On the subject of cheek weld and stock design, I may have made a new discovery. YouTube is full of people cursing and struggling with the bolt on the Mosin-Nagant. I can see why since the spring is strong enough that the fairly narrow stock will roll in your hand as you try to open the bolt. But I’ve found that by retaining cheek weld and using it to apply opposing pressure on the stock as it tries to roll, the bolt will open easily enough. It won’t be as fast as a Lee-Enfield, but it is only a little slower. It feels very nice too. If part of the joy or working a bolt is to hear and feel the mechanism working, then it’s hard to beat a Mosin as it clanks authoritatively through the bolt cycle.
Mike, I wonder if a taser would have worked on the crazy woman in Baltimore. Obviously, she was on some drugs that were altering her physiology in a really deep way. As I understand it, tasers work directly on the nervous system by interfering with the generation of electric charge down nerves that allow them to function. This would seem to be pretty effective. On the other hand, human beings are not supposed to be able to take multiple strikes to the head that could fracture the skull or be able to break through tempered steel handcuffs. Don’t know. Wouldn’t want to be the one trying out the taser on her.
Shok, the photo series of the upside down rhino was of some attempt to save rhinos by tranquilizing and relocating them. I thought it looked very funny. Imagine if the rhino woke up. And would the helicopter be able to manage if he started thrashing around?
I’m a fan of things Russian. But I must say that I would pass on most of these.
http://news.yahoo.com/photos/coffin-culture-evolves-in-russia-1320796296-slideshow/#crsl=%252Fphotos%252Fcoffin-culture-evolves-in-russia-1320796296-slideshow%252Fartist-decorates-hand-made-coffin-displayed-nekropol-2011-photo-064907742.html
Matt61
There may be someone that the Tazer won’t work on…………but I haven’t seen or heard of it. It’s kind of like a full body Charlie Horse!
Mike
“Earlier, Rashaun Yusef Stevens, 20, of Roswell was arrested, and Alpharetta police said they recovered from a gold Acura TL the high-powered pellet pistol allegedly used in the attacks.
Authorities charged both men with aggravated assault with a firearm and two counts of criminal damage to property in the first degree, all felonies. They also were charged with criminal trespass.”
above is from here…
http://www.ajc.com/news/north-fulton/2nd-suspect-arrested-in-1220550.html
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I did not know pellet guns are considered a firearms. ??
Gene,
In many (most? all?) states, anyone who commits a crime and uses an airgun or airsoft gun or anything that’s not a firearm but is portrayed and presented as though it’s a firearm, is usually charged as though it IS a firearm.
People used to get away with crimes by using airsoft guns that did not have orange on the muzzle but portraying the guns as firearms when accosting people. As a result, the bad guys were getting off on a technicality. Eventually, the law caught up and said that if you pretend something’s a firearm during the commission of a crime, then we’re going to treat you as though you committed said crime with a firearm.
Also, I’ve found that journalists/writers who know little about airguns and airsoft guns have no problem with identifying every gun as a firearm. The story you cite may not be accurate. Maybe this person was not charged with assault with a firearm.
Edith
Gene,
any type of pellet gun other than an airsoft gun, is considered a firearm here in the wonderful People’s Republik of New Jersey.
Fred PRoNJ
In most places, now, if you stick a finger in a jacket and say “stick ’em up’, the law will agree and charge accordingly (if, of course, they bother with you…). And I tend to agree with Edith; it’s necessary.
Edith
Having extensive experience with the Atlanta Journal and Constitution, I can tell you that any given story published there is likely to be inaccurate. They are one of the worst newspapers in the country. You can’t even trust the crossword puzzle.
I’m more concerned with the “high-powered” pistol image… My single-stroke pneumatic Daisy 717 is more powerful than a CO2 powered “semi-auto” look-alike (in my case, the CP99 — using a new CO2 cartridge and 7.7gr RWS Superdomes, the CP99 managed all of 330fps/1.87ft-lbs vs 717 and 8.3gr RWS Meisterkugeln Rifle achieving 376fps/2.6ft-lbs).
However, to put things in perspective, in Michigan, if it is larger than .177 and/or has rifling (IOW, it is not a smoothbore BB gun) — excluding red-muzzle AirSoft I believe — obtaining a pellet pistol requires one to go through the same paperwork as a powder burning pistol: go to local police department (or sheriff if in an unincorporated area), fill out the “application for permit to purchase”, get it notarized, signed by chief of police/sheriff [once signed the other side IS {or was, my last Michigan purchase was 1980, and the forms were triplicate with no carbon paper} the permit to purchase]. You then have 10 days to purchase a pistol (from any dealer in the state, any pistol). THEN you have, as I recall, another 10 days to return the purchase permit (less dealer copy) to the issuing department AND fill out the “handgun safety check” papers (AKA: registration; the chief didn’t care about how the T/C Contender safety functioned, only the serial number).
If you move to the state, you still have to submit handguns to the “safety check” (which is why it is good I did not buy a Marauder Pistol — since the shrouded barrel is illegal; what the state doesn’t know about my Marauder Rifle won’t hurt them). Going to be a busy December when I finish relocating (I think the cap&ball revolver is exempt, but that still leaves me with four semi-auto handguns, re-registering the Contender, the 717, Crosman Silhouette, and Baikal IZH; I sure hope they’ve computerized the data entry by now)
Wulfraed,
That’s horrible! I hope in the next election we can vote out these POS’s and begin to turn the regs around to something reasonable. I can’t imagine having to go through all that just to teach your kid to shoot…. A smoothbore Crosman 760 will stick a pellet in you just as easily as a “rifled” Benjamin. Probably easier since the 760 is easier to pump. Makes me wonder just what kind of idiots wrote these laws. It’s no wonder that Detroit and surrounding have such high crime. Criminals there don’t have to be afraid of anything. 🙁
/Dave
Considering how many decades the “handgun safety certificate” has been in existence, it would require a nuke over Detroit, and an effective “gunpowder plot” in Lansing, to make enough openings to have a chance of revoking those laws.
OTOH: Michigan IS a “shall issue” state as opposed to California “my cronies” permits…
Oh, and I do need to emphasize, the paperwork hassle is for handguns (like the CP99, Daisy 717, or the Baikal… or Crosman Silhouette). It doesn’t apply to long guns, and I doubt the dealers are requiring BATFE papers on purchase…
But it did mean little selection in pellets… I think MC Sporting Goods only had three types of .177 pellets in stock: a wadcutter, a domed, and a pointed.
Wulfraerd,
I’m from California and I have to say that’s HORRIBLE! Where’s the reasoning in that?
/Dave, I’m all for voting out the sh-t we’re stuck with in Congress, The House of Reps and especially the White House, but to vote ’em out blindly is what happened last time and look what we ended up with, the most disgraceful POS America has ever seen, not to mention her husband, the President who’s screwing up every ally tie we’ve had since WWI! Arrrrgggg!!!
ka
KA,
I know what you mean. Some guy comes out of nowhere, has never really had a job, promises change, and the sheeple all say, “Our savior! Let’s give him the keys to the kingdom!” Without even knowing what kind of change is being proposed……
Wulfraed,
That’s still pretty darned restrictive. I didn’t say that it would happen in one election, but hopefully the sheeple will wake up and at least start the process….
/Dave
There may be people that the Tazer won’t work on……………..but I haven’t seen it or heard of it. It’s kind of like a full body Charlie Horse!
Mike
Bill,
I think you have a broken mainspring. It’s very common in a Diana 34/36/38.
B.B.