by Tom Gaylord, a.k.a. B.B. Pelletier
Today, I’ll report on the final test in this series. This isn’t the final report — just the final test, which is the barrel with the 1:12″ twist, shooting at 50 yards. Get ready to be surprised. I know I was!
I did this test on the same perfect day as the factory barrel that was reported last week in Part 10, and the weather was perfect most of the time. From time to time, there was a very slight breeze that I waited out before shooting. The shooting conditions were as good as they get.
Changing barrels took 5 minutes. The silver barrel has the 1:12″ twist.
I used the same two pellets we’ve been shooting all along, and they were shot at power settings 6 and 10…just like the other 2 barrels that went before. The gun was shot while resting on a sandbag that’s very stable. When the tank was filled or the power was changed, I always shot one shot to settle the valve. Experience tells me that’s all that’s needed.
The tank was filled to 3,000 psi.
Power setting 10
I first shot both pellets on power setting 10. And 14.3-grain Crosman Premiers were hitting low and to the left. One of them only nicked the target paper, so I photographed the target before taking it off the backer paper, so you could see the complete group.
Here are the two 10-shot groups of Premiers. Notice that they’re hitting to the right of the aim point, which is the center of the bull they touch. The group shot on power setting 10 is at the top, and it shows why I like to use backer paper when shooting at 50 yards.
Premiers on power setting 10 gave this 2.577-inch group. See the nick on the right edge of the target paper? I had to guess a little for this measurement, but it isn’t too far off.
Then it was time to test the 15.9-grain JSB Exact Jumbo 15.9-grain pellet on power setting 10. This is where the surprise comes! Ten pellets made a 1.259-inch group! If you check back with the results the factory barrel gave, you’ll see that this group is very close to the best group made by the factory barrel (1.153″ for 10 shots with the same JSB pellet on power setting 6), and it’s equal to the group that was shot on power setting 10 (1.283″). This addresses a question many of have had from the beginning of this test — namely, are the Quackenbush barrels equal to the Lothar Walther barrel?
JSB Jumbo 15.9-grain domes on power setting 10 gave this 1.259-inch group. This shows that the 1:12″ barrel can be accurate at 50 yards.
With so little data, it’s impossible to say if these two barrels are exactly as good, but what we now can say is that one of the Quackenbush barrels gave some groups that are at least equivalent to those from the factory barrel. The difference is so small that it might be due to the twist rate rather than the quality of the barrels. That was the position I took at the start of the test, and I think this demonstrates it was valid.
Power setting 6
Next, it was time to test the 1:12″ barrel on power setting 6. Ten Premiers went into 2.234 inches, which is only slightly smaller than the same pellet on power setting 10. As before, the pellet stuck the target low and to the right.
Ten Crosman Premiers on power setting 6 gave this 2.234-inch group. This is similar to the group that was obtained on power setting 10. The difference is too close to call.
It’s official — the 1:12″ barrel does not like Crosman Premiers out at 50 yards. But that wasn’t the only pellet in this test.
With JSB Exact Jumbo 15.9-grain domes, the barrel did nearly as good on power setting 6 as it did on setting 10. Ten pellets made a 1.363-inch group. Like the Premiers, the JSBs also performed about the same on setting 6 as on setting 10. But that’s not the real lesson. The real thing to note is that the 1:12″ twist barrel was not as good at 25 yards as the factory barrel, yet at 50 yards it almost caught up. In other words, the accuracy of the factory barrel degraded faster as the distance increased than the barrel with the faster twist.
Ten JSB Exact domes on power setting 6 gave this 1.363-inch group. Like the Premiers, this result is also very similar to the group that was obtained with this pellet on power setting 10.
What has been learned?
This is not the final report. I’ll add these results to the previous summary report given in Part 9, and we’ll be able to see all 3 barrels at all 3 distances with both pellets at all 3 power levels. But if I had to give a quick analysis, I’d say the 1:12″ twist barrel surprised me at 50 yards by being better than I expected. At least it was better with the JSB pellets.
And that fact alone — that a barrel can be so much better with one pellet than with another — is good to know. This test has demonstrated that principle beyond all doubt.
A lot more testing needs to be done to thoroughly see all the relationships, but I’ll tell you what I know in the next report, which will be the final report for this series. I think we can advance our knowledge of how pellets perform by quite a bit by combining the results of this lengthy test, the smoothbore test and the pellet velocity versus accuracy test. We’ve been exploring this theme for nearly 2 full years now, and I think we’ve learned a lot!
68 thoughts on “How does rifling twist rate affect velocity and/or accuracy: Part 12”
BB. In the top photo with the 2 barrels, what type of end cap is that and does it help to quiet the gun?
The end cap itself is a standard Talon SS end cap that has some baffling added to it and I am quite sure that it is much quieter than the standard Talon SS. I am curious as to whether BB has a hammer slap modification on that TSS to quiet the hammer slap some.
That’s a cap we made at AirForce to quiet the SS a little more. It works, but isn’t as dramatic as you might think. It was never put into production.
Ok thanks. Thought maybe it was something aftermarket. Have you had a chance to try out the new Sound loc Kit for the Talon SS yet? Put it in mine and makes a very noticeable change in sound.
I have one on order from PA. Should get here tomorrow.
Twotalon I think you will like it when you get it. Very simple to install. Just like changing the barrel.
This is my first Airforce gun so first time pulling the barrel out and had no problems with the install.
Should be easier for me. Just pull the endcap and drop in the parts I want.
Twotalon you have to take the barrel out because it comes with 2 new collars that mount on the barrel.
The back one is solid with a o-ring on it to seal to the outer shroud/body of the gun. And the front one closer to where the pellet leaves the barrel has if I remember right 5 air passage holes drilled in it. Of course unless you already have your stock ones modified.
Either way still easy to do.
Drilled the front ones out on both of my short barrels years ago.
Twotalon I figured you would probably already have something done to them that’s why I mentioned that.
But the one that goes closer to the receiver end of the barrel has that outer o-ring on it. I believe they put that one there to keep the sound from exiting by the power wheel area. Just a guess on my part. Not sure if that is the true reason though.
I think it is to stop air from blowing in your face. Could be some pellet dirt in it.
No, I haven’t done that yet. I was waiting to finish the barrel twist test first.
I thought maybe you had some of this top secret equipment already you have been testing in secret. B)
My cool smiley face didn’t work out. B-) Lets see if this works.
The heavier JSBs hit the paper higher than the premiers at the same power settings in both cases. I always thought that the opposite would be true. In my springer, Barracudas generally hit paper approx 1″ lower @ 20 yds compared to premiers and other lighter pellets. Why do you think this is happening??
If you look back at part 3, you will see that the CP were slower than the JSB on power setting 6, and a bit faster on power setting 10. So let’s say that they were equal to simplify things. The B.C. of the JSB is a lot higher with the JSB. They retain velocity better and should strike higher.
Let’s leave springers out of this….P.O.I. changes a lot due to recoil . Don’t equate this to what a PCP is going to do.
That sounds like a good explanation to me.
Is it the better BC of the JSB or a heavier pellet reacting favourably to a faster twist rate??
Perhaps B.B. can repeat the test using two different pellets with similar weights and let us see the results .
My choice would be:-
JSB Jumbo Express 14.3gr and Air Arms Diabolo Field 16gr ( both domed pellets). You and B.B. are the experts and can work out the BC of all four pellets. I haven’t got a clue how to work out the BC of a pellet.
If you leave out the possibility of a consistent corkscrew as a reason for a different P.O.I. , ignore the size of the groups, and ignore the possibility of a difference in barrel vibration, then it is the B.C. of the pellet that makes the vertical difference in P.O.I. in this case.
You can have heavier pellets with a worse B.C. than lighter pellets if you choose the right pellets to compare also.
I look up B.C. from Chairgun. I have only done one actual shooting session to determine B.C. , and that was with .177 Raptors and Jsb RS. I was simply curious to find out what the B.C. was .
Also (should have included this ), working out B.C. can be done two different ways…
Shooting at two different distances and feeding the difference in P.O.I. and distance between targets to Chairgun , or by shooting over a chrono at two different distances and feeding the distance between targets and the two different velocities to Chairgun.
There will be some error. The greater the target distances or chrono distances are apart, the better the result will be.
The initial velocity will change the B.C. a little because B.C. is not constant….it changes with velocity , and different rifles shoot with a different B.C. possibly because of differences in pellet deformation in the barrel even when shot at the same velocity and pellet.
I should proof read my comments, since I can’t edit after pushing the button.
You can’t fool me !! You shot those Crosman groups with a stoned sewing machine !!
Again I tip my hat to you BB…..you have an uncanny ability to present very complex experiments and concepts in a way that anyone with a grain of interest can learn from.Thank you for unselfishly and patiently sharing that with us.
It is interesting that the Premiers were more accurate at 10 Meters and at 25 yards than the JSBs with the 1 in 12 barrel but at 50 yards the JSBs are more accurate than the Premiers. I have always been under the impression that barrel accuracy was kind of like a shotgun pattern. The closer up the tighter a group was and it keeps opening up as the distance increases. Well, I guess that is not totally true. I know that wadcutters group well at close distances but the groups open up more quickly that domed pellets.
I guess to pick the best pellet for a gun you need to to first decide the distance at which accuracy is more important and do your pellet testing at that distance.
I think we are all learning from this. I know I have several firearms applications to apply this learning to. Maybe they will now make some sense. Nothing is straightforward, it seems.
A few months ago, we announced that the old blog on Blogger was going to be discontinued. Pyramyd Air would be moving the old blog postings to this one. Apparently, that will be happening sooner than I was led to believe. I’d like to thank blog reader GenghisJan, who told us there was a way to move the posts without losing the comments. I’ve sent that info to Pyramyd Air, and they’re researching that right now.
Because they have to make some conversions to the old blog in order to retain the comments, it may not be available for a little while when they actually proceed with the work. So, if you try to go to an old posting on Blogger (listed on this site as the historical archives) and it doesn’t come up, it’s most likely due to the mandatory conversion.
Edith I hope that goes smooth. I have went back at different times looking for info on something I was trying to do. So I hope it all gets moved ok.
Good to hear that they can keep the old blog in its entirety. They say that everything lives forever on the internet. That would be unfortunate if we were an exception.
Best of luck! Preserving this amount of information is priceless.
Maybe that’s an unneeded extra, but… If I were to keep the info, I would fist make a blunt copy-paste of everything, and only then allow the software to convert something. Difference between software and material world is that software can work perfectly even if there are huge mistakes in it and the result is some mishmashed data.
If I had that much control over the situation (and the time), I’d make a backup. But I’m not in charge and have barely enough time to sleep.
I’m still curious as to what a longer pellet like the Eun Jin will print at 50 fired, from the faster twist barrel. Maybe try that and some of the other hyper heavies sometime before changing your barrel back?
For this experiment, maybe another chart/graph incorporating all of the test info on one page might be helpful. I don’t know if trend lines can be included, but they would really tie it all together…
I will take this under consideration. It will not be part of this test, if I do it.
I would be interested in the results of the longer pellet also. This is good info.
I’m not going to mess around with the barrel on my Talon SS or mod it either. Other than the Sound Loc Kit I have in it. But I do plan on getting a Condor SS at some point in time. That is the gun I will do some changing around on. I like the longer range shooting. Gives me a challenge when I shoot.
So all this info is perfect timing for me.
Wow! Now that’s quite expected. I believe that’s due to JSB being longer, so they must behave better at slower twist and the faster the better rule works too. I wonder if you could test it with even longer pellets, e.g. Exact Jumbo Monster.
Again and again – thank you for your scientific and practice efforts!
They are asking me to test this barrel with an Eun Jin 28.4-grain pellet at 50 yards for exactly that reason. So I guess we will have more to learn.
I believe Jumbo Monster would be closer to original weight – and much more uniform than Eun Jin, so results would be much “cleaner”
Tell you what. I will try it with both Eun Jin and JSB Monsters. Naturally I will also test them in the factory barrel.
You definitely know how to make people jump on their seats form agitation 🙂
Twotalon had to move down here. Getting to thin up there.
But you are probably right about why they put the back o-ring there. And maybe also to keep the power wheel adjuster clean.
They will blow in your face if you restrict the exiting air by enough. Wonder how I know that ?
I doubt if keeping the power adjuster clean was a consideration.
TT. Yep I know what you mean. Live and learn.
But check out how they made the baffles when you get your Sound Loc Kit. They made the slots in a different way than I would of thought. See what you think when you get your kit.
B.B. and Edith,
My two posts far above were in response to a few trolls/spammers whose comments have since been removed. I kindly ask any of the powers-that-be to delete my two posts as they are no longer purposeful or make any sense without that context.
It’s best to just not respond to those posts. We will take care of removing them.
So does Dennis Quackenbush, as a one man operation, make all of his barrels by hand? I would have thought that a big operation like Lothar Walther would have perfected some kind of manufacturing operation to turn out barrels of a uniformity and quality that no human could match. But I was kind of surprised to hear about the individual work involved in the making of barrels for Savage rifles which are as accurate as just about anything else–judging by the performance of their factory rifles in the 1000 yard world championships. Apparently, they have a small number of experts who look down the barrels and do some kind of final straightening and adjustment by hand. Wow, I guess there’s still no beating the homemade.
I was just reading in Chris Kyle’s book that the many of the Springfield Trapdoor rifles of the old West were actually Springfield 1861 muskets from the Civil War which had been modified by having their breeches cut upon and fitted with the new action. It was the Ordnance department being their tightwad selves. But if you could get your hands on an original of those rifles you would certainly have a lot of American history in your hands. Kyle does have a talent for pulling out the salient fact or event which is the kind of history that I love. He said that at one trading post in Texas, some small number of settlers were ridiculously outnumbered by Indians and fighting for their lives. During a break in the action, some guy took out a “Sharps big .50” and shot some Indian off his horse at a measured 1538 yards as measured by army surveyors who showed up later. This broke the morale of the Indians, and they rode off. How about that for iron sights and an old-fashioned cartridge?
Kyle also has a description of the fabled gunfight at the O.K. Corral which I had heard much of but never read about in detail. It sounded like pure chaos, and even to this day no one really knows what happened. But generally it sounded like lawmen who were not a whole lot different from the thugs they confronted wiped them out through a mixture of aggressiveness and luck. It also sounds like the people in the Wild West mixed alcohol and guns pretty frequently and that some people made a habit of being more or less constantly drunk. In other words, it sounds like a lot of other violence in the Old West that does not live up to its mythology.
One exception would be Wild Bill Hickock. It was said that when angry, his normally friendly blue eyes would get “hypnotically” cold. And in one famous shootout, he used his pistol to fatally shoot some guy standing sideways in the classic dueling pose at a measured 75 yards away. That is quite a feat.
By the way, on the subject of actors, I picked up a paperback from the Jack Reacher series which was the basis of a recent film by Tom Cruise. The “real” or original Jack Reacher is 6’5″. And in a clip from the movie, you can see Tom Cruise staring up at an assailant from a considerable angle. Heh, heh. At least, the producers of the film Casablanca had the good sense to put Ingrid Bergman in a trench when it was found that she towered over Humphrey Bogart…
Yes Dennis makes all his own barrels. And, no, a big company like Lothar Walther cannot make the finest barrels. The finest barrels are made one at a time in small shops that put more manhours into them that a big company can afford. Companies like Lilja, Shilen and Douglas make some of the finest barrels, and there are probably smaller makers who do even better.
Lothar Walther makes a fine barrel, make no mistake, but when the prizes are on the line, shooters choose the boutique makers.
That doesn’t hold true for air rifle and smallbore competition barrels, however. Feinwerkbau, Anschuetz, Steyr and Walther probably make the best of these barrels.
BB one thing I haven’t seen you mention is the cost of these aftermarket barrels. In no way I’m trying to put down the manufactures of these barrels. I know alot of time goes into making quality pieces.
Believe me I spent money on the car stuff when I was big into drag racing. But is the cost reasonable for a everyday average fun shooter to go after one of these special barrels. If they really are better at grouping the shots maybe I want one.
I like the result I see with the 1:12″ barrel. And it only makes me think it would group good out at farther ranges. But again you never know.
Oh, just forgot to tell – tomorrow I’m leaving for London. Maybe that’s the closest to you or some of this blog’s readers.
How long will you be gone?
Two, maybe three days. Purely business trip.
BB I’m thinking about trying the Eun Jin .177 cal. 16.1 grn. round nose in my Talon SS. I will have to order some though. So this is what I wanted to find out before I ordered.
Trying to slow the pellet down to make the gun a little quieter and still have a reasonable fpe.
I have been shooting the 10.3’s in the gun.
And what I noticed is the gun is quiet if I dry fire it. But when I load a pellet and shoot; the gun seems to be making a slight crack like the pellet is going sonic. Which is making the gun louder than it should be for my liking.
The heaviest I have is some 13.3 dome pellets. It seemed to me that the report was quieter and was still hitting the mark at 50 yrds. Still haven’t chronyed the gun yet so not really sure what fps. it is shooting at.
I know your talking above about doing the test. And it is with the .22 cal. pellets. And I should be really asking the question on the Condor SS report.
But do you think the Talon SS with the standard tank has a chance of shooting that heavy pellet in .177 cal. ?
And from what I have seen slowing the fps down usually makes things quieter. But I have never shot anything that heavy in .177 .
If it’s accurate, then, yes, it works. That’s the criteria.
It’s NOT going supersonic. No way in a short barrel.
Get it on the chrono and don’t set the power wheel any higher than it takes to come up to max speed for your fill pressure. The setting will change between different pellets. Remember to shoot once after each adjustment before you look at the chrono..
I didn’t think that they would be going that fast either. But to me it was odd that the report got louder when firing the pellet.
The Marauders and 1720T make pretty much the same sound with or without a pellet.
I read some of the reviews for the .177 cal. Eun Jin and people seem to be having good luck with them when using them in the Airforce guns. So I’m going to give them a try.
And if I remember right these pellets were around when I was kid but I think they had a different name. Never got none back then because I didn’t have anything strong enough to shoot them with.
And I do need to get the gun on the chrony for sure. But I like the tune it has now. So I don’t know if I will like the results of the heavy Eun Jin’s.
I just hope they are easy to load. No bolt on the Talon SS. Thumb can only push so far.
When you dry fire it, there is not nearly as much back pressure as there is with pellets. So the valve closes faster….delivers less air. Since there is less pressure in the barrel, the sound will not be as loud as with a pellet.
The 12″ simply can’t go supersonic. To do that, you would have to use the 18″ .177 and shoot the pot metal rat droppings (PBA). Pellets around 10 gr will shoot about 1,000 fps with the 18″.
Makes sense about the back pressure and the valve.
And that’s what I have been shooting is 10.3 grn. pellet. The way it hits I’m sure its got to be around 1000 fps.
But I got to wait till Friday to chrony the gun when I’m off work. I should have the Eun Jin’s by then also.
I’m going to leave the power wheel set at 4 and check the fps. with 3 different pellets I will have in .177 cal. That way I can see how much the fps. drops with the heavier pellets.
The 8.3 Superdomes, AirArms field heavy’s 10.3, and the Eun Jin’s is what I have.
Expect lower to mid 800s with JSB heavies, Kodiaks, and CPH with the 12″ . The EJs will be slower.
SD pellets have a crummy BC.
Maybe it will help the noise some then. That’s what I’m after is less sound and still have accuracy and knock down power.
Boy I don’t want much do I.
Any time noise is a problem (legal situation or not), then we all want the same thing.
Knock down ? 9 out of ten starlings agree that being within 60 yds of the TSS is a bad thing. I have taken out full grown coon at 25 yds with a head shot using CPH.
It will do more than you think it would if you are careful about it.
Have to evaluate outside for reflected noise quality to decide on the noise reduction system.
My TSS .177 cal. Chronyed at 1030 with the Superdome 8.3. Air arms 10.3 at 960, and also had some Jsb exact 13.3 they went 880. Eun Jin’s went 705 fps. All power setting 4.
Then I shot them at the targets. All good except the Eun Jin’s. Some of the Eun Jin’s shot good and some tumbled. Didn’t like the way they loaded either. Hard to get in once you were close to the skirt.
Air Arms 10.3 were the best. Also had the quietest report.
Tryed all of them at 6 and 10 on the power wheel and there was not that much increase in fps. and I had to refill the tank sooner because the pellets started dropping off sooner. (less shots per fill)
I made some baffles also but need to try them yet.
Looks like it is a bit on the hot side, but I would guess that you are running your fill right at max.
E-Js have a reputation for hard loading. Never tried them.
Yeah, it will really suck up air won’t it ? See where it is starting to max the velocity and stop there with the power wheel.
Yoy need to check all the barrel mounting screws and the tophat screws to make sure they are snug. Don’t overtighten. Careful of the endcap screw . Not tight enough and you might be ordering a new one from PA. It will land somewhere in the next county, along with the baffles.
Been without power for over 3 days, and running on generators. power came back on last night before dark. Had a bad storm that resembled a hurricane . Lost some good shooting weather because I spent two days cutting up a big tree.
Want any brush or firewood ? It’s free. How about a pile of bent up sheet metal that used to be the lawnmower shed ?
GF 1 Sorry about the GR1. Sun in my face. Can’t see too good.
Bummer about the storm. Main thing is everybody ok? And no problem about the mis spell.
Still using the 2500 down to 1500 psi fill pressure.
I did tryed the Eun Jin’s up at 3000 to see if it would help to keep them from tumbling and chronyed them also at that fill pressure. Fps dropped all the way down to 595 and the impact of the pellet dropped about 2″ lower. I fired 10 shots of them and half of them tumbled this time. And they made the most noise at both fill pressures out of all the pellets.
I think I got a little tighter barrel or something with my TSS. I tryed the Eun Jin’s in my .177 Marauder and they didn’t seem to be as tight loading in the Marauder. But the results were about the same as the TSS when I shot them. There was only a few that tumbled which is better. But only one tumbling is to many for me.
They called me into work today so I have to wait till tomorrow to try the baffles I made.
Sounds like you are encountering partial valve lock.
That’s what I see happening too. Experienced this with the Benjamin and Crosman guns also.
There is things you can do to over come this as I’m sure you already know.
I got the 10# spring in my M-Rods. But I don’t have the spring pressure cranked all the way up either.
I want the extra power but I want to maintain accuracy ( Just like a springer if I tighten the spring; the gun will be harder to control). So if you use the spring modification in moderation you can have a wide range of tune.
I was thinking about putting the striker weight in the TSS but I’m very happy with the results of the TSS the way it is set now. My main concern has been noise reduction. And I got that under control now also.
hello! B.B. Pelletier … there are different barrel twist rate and also different numbers of grooves some have 6 grooves some has 8 or 12 my concern is which of these barrel is best for an airgun?
There aren’t many different twist rates for airguns. One in 16 inches is standard.
Most shooters prefer the 12-groove barrels. I have had good luck with all of them, because the barrels with fewer grooves still have narrow lands, which is the real secret.
hmmm, you made it clear! thank you and more power to your blog