How does rifling twist rate affect velocity and/or accuracy? Part 9

by Tom Gaylord, a.k.a. B.B. Pelletier

Before we begin, there was a request last week for me to test the Benjamin 392. I thought I’d tested it already, and it turns out I did. Click see all 5 parts on the old blog.

Part 1
Part 2
Part 3
Part 4
Part 5
Part 6
Part 7
Part 8

The question of barrel equivalency
Today, we’ll look at the accuracy side of this test, where yesterday we looked at how the twist rate affects velocity. Before I begin, however, we have to settle an issue that’s in a lot of people’s minds. Namely, is it reasonable to test barrels made by Dennis Quackenbush against a Lothar Walther factory AirForce barrel? Will the test results be skewed for that reason and not because of the different rifling twist rates? Or will the twist rates determine part of the results and the barrel’s pedigree determine the rest?

To carry that kind of logic out to its conclusion, every barrel will be different. Who’s to say that one Lothar Walther barrel is not better or worse than another? The fact is that we know that some of them will stand apart — being either better or worse than the norm. There’s no way to test the exact same barrel with all 3 twist rates because we cannot adjust the twist rate of a rifled barrel. Once it’s built, it is whatever it is. Three separate barrels have to be used for this test, whether they’re made by Lothar Walther or by someone else.

Another thing to consider is that other smallbore barrels made by Dennis Quackenbush in the past have proven to be as accurate as barrels made by Lothar Walther. I’m now talking about barrels of the same caliber — not comparing .22-caliber Walther barrels against .308-caliber Quackenbush barrels. I know of .22-caliber barrels and .25-caliber barrels made by Quackenbush that can go against the best barrels made by Lothar Walther.

But in the end, we can never know if the barrels I’m using for this test are exactly as accurate as the Lothar Walther factory barrel I am also using. There is just no way to know that. There is, however, a way of getting pretty close. If the Quackenbush barrels produce some groups in the same accuracy range as the Lothar Walther barrel, then we can be assured that we are testing barrels of similar quality. We can never be entirely certain they are exactly as good, so this is as close as it is possible to come. And, by the same logic, that is all we could do if Lothar Walther had made all 3 barrels used in this test.

Lothar Walther is not going to make test barrels for a test like this unless they want to. There is no way to contract with them to make one-off barrels that have the different twist rates we are testing. They don’t make one-off barrels — at least not for the public. There are barrel makers who do make one-off barrels, and Dennis Quackenbush is one of them. We’re going to have to be satisfied with the barrels he has provided and look at the results to see if we believe his barrels are as good as the factory barrel we’re testing.

On with the test
With that issue set aside, let’s look at what the 3 barrels did in this test.

Rifling twist rate and accuracyThe group sizes in the table are shown in inches.

General observations
The first thing I looked at was the results of the 2 Quackenbush barrels against the factory Lothar Walther barrel, and I learned something interesting. At 10 meters, the 1:22″ twist barrel shot better than the factory barrel with Crosman Premier pellets — not by a little, but by a significant margin. On both zero and 6 power, the 1:22″ barrel made groups that were one-tenth of an inch smaller than those made by the factory barrel. On power setting 10, the factory barrel beat the 1:22″ barrel by only four one-hundredths of an inch. I think that’s significant. It shows that the 1:22″ twist barrel can keep up with and even exceed the Lothar Walther barrel…at least to 10 meters.

The 1:12″ twist barrel wasn’t quite as good as the factory barrel at 10 meters, but it was very close. At power settings zero and 6 they differed by just a few thousandths of an inch. On setting 10, the factory barrel exceeded the 1:12″ barrel by the same four one-hundredths of an inch that it did with the 1:22″ barrel.

These results tell me that the two barrels made by Dennis Quackenbush are as capable of making good groups as the Lothar Walther barrel. The differences in the group sizes are less than the measurement errors made when measuring the groups. That puts the barrel equivalency question to rest in my mind. I’m willing to accept that the results of this test are from the different twist rates and not from the inherent quality or lack of quality of the barrels being tested.

Ten meters is really too close for definitive results when the question of accuracy is on the line. That’s why the test was also shot at 25 yards, and later I’ll shoot it at 50 yards. It was at that distance that the factory barrel really shined. With 14.3-grain Crosman Premiers, the factory barrel was more accurate on power setting 10 than on the lower settings. With 15.9-grain JSB Exacts, the factory barrel did its best on power setting 6. But both of the other barrels did not perform their best at this range.

The 1:12″ barrel shot Crosman Premiers best on power setting 6, but it shot JSB Exacts about the same on settings 6 and 10. There was a little difference with the Exacts, but it was down in the measurement error margin.

The 1:22″ barrel, on the other hand, got worse with Premiers as the power was increased. And the difference between the best and worst groups was large enough to be more than a coincidence. It was almost twice as large on power setting 10 as it was on power setting zero (1.082″ compared to 0.671″).

With JSB Exact pellets, that trend was reversed. The greater the power, the smaller the groups became. For both pellets at 25 yards, the 1:22″ barrel was not anywhere near the factory barrel at the same distance. Only at power setting zero with Premiers was that barrel close to the factory barrel, and the difference was still outside the measuring-error margin.

The 1:12″ barrel performed similar to the 1:22″ barrel at 25 yards. Only once, at power setting 6 with Premier pellets, did the 1:12″ barrel exceed the factory 1:16″ barrel.

If you look at the results of the 1:22″ barrel, you’ll note that it falls apart at 25 yards. It held its own at 10 meters; but at 25 yards, it falls far behind the factory barrel.

The 1:12″ barrel does the same, but it doesn’t open up as much as the 1:22″ barrel. There are individual instances where one of the two Quackenbush barrels exceeds the other; but in general, what I’m saying holds true. The factory barrel, however, doesn’t work that way.

The factory barrel holds together at 25 yards, just as it does at 10 meters. Again, there’s a single instance at 25 yards where it is beaten by the 1:12″ barrel (power setting 6 with Premier pellets), but that stands out as the only time the factory barrel was beaten at 25 yards. We can say in this test the factory 1:16″ twist barrel outperformed the other two barrels at 25 yards. That allows me to say two things.

First, I predict that the factory barrel will be the most accurate at 50 yards. Second, I believe that the 1:16″ twist rate is the best twist rate of the 3 we’ve tested.

Don’t get too excited
This test has been too small to say anything with certainty. I said that before we began, and I’m saying it again now. All these results can do is suggest things that should be looked at more closely. Other pellets will give different results — I’m sure of that. And more testing will refine these numbers. Where there’s gross separation between the Quackenbush barrels and the factory barrel, I feel certain the trend will continue with more testing. But where things are close, there might be a reversal of the outcome. There simply isn’t enough test data to say otherwise.

Conclusions so far
Based on the data we see thus far, I think that the 1:16″ twist rate seems to be the best of the three twist rates we’ve tested. At 10 meters, the factory barrel shot 3 of the best 6 results. At 25 yards the factory barrel shot 5 of 6 groups better than the other 2 barrels. Out of the total of 12 results, the factory barrel was the best 8 times. So, 67 percent of the best groups in this test were shot by the factory barrel.

The factory barrel is the best overall barrel in this test so far, and it gets better the farther the distance is to the target.

Because the other 2 barrels beat the factory barrel one-third of the time, I think the question of their quality can be laid to rest. Clearly, they’re giving the Lothar Walther factory barrel a run for the money.

Power versus accuracy
In Part 8, I talked about not needing to use power setting 10 with the 1:22″ barrel if it proved to be accurate enough. The velocity at power setting 6 was so high that I said I could stop there and conserve air. I think I’ve now shown that it isn’t accurate enough. Yes…when you look only at that barrel’s accuracy, you could surmise that it’s accurate enough at power setting 6 to stop at that point. But when the factory barrel is brought into the equation, the 1:22″ barrel falls behind.

What’s next?
Next, I’ll shoot all 3 barrels at 50 yards. I’m planning to shoot only power settings 6 and 10 with each barrel because of the distance involved. This will be outdoors, and the pellets will really scatter in the light breezes if they’re shot on the lowest setting. I will have to wait for ideal range conditions, so it may be quite a while before I’m able to make my next report.

42 Responses to “How does rifling twist rate affect velocity and/or accuracy? Part 9”

  • RidgeRunner Says:

    This is like so cool! I enjoy R & D! I would like to find someone to pay me to stay at home and do this kind of stuff. The main issue I would likely have would be producing reports.

    If I was a competition shooter AND rich, I might have to consider having some barrels of different twist rates made. There is a marked improvement at low power at 10 meters with the 1:22″. If you are up to it after all this testing, you should try these barrels in the Edge. If not, I would e more than happy to do such for you. ;o)

    Maybe some of the manufacturers will take note of this spiel and do a little R & D of their own.

  • feinwerk Says:

    The kinetic energy delivered to the pellet is divided between the linear velocity and the spin rate. For a given velocity and spin rate, the linear energy is a function of just the speed and pellet weight. However, the rotational energy depends on something called the moment of inertia of the pellet, which is related to both the pellet’s weight and how it is distributed throughout it’s cross section. The way the energy divides between linear and rotational will vary with each pellet. The stabilization depends partly on the aerodynamics of the diabolo shape and the gyroscopic effect. What a complicated interaction!
    It’s no wonder then that it takes so much trial and error to determine which pellet shoots best in a given gun and velocity. The two pellets in this test are similar in weight, as Duskwight pointed out. In many of my .22 airguns, a heavier pellet performs better. I’d sure like to see how the 18.1 grain JSB heavies would do in this test.
    B.B., is the 16:1 rifling twist rate fairly standard for airguns? Is it different for firearms? I imagine that at some point in the development of guns that makers experimented with twist rates and determined which provided the best overall performance. Thanks for all your fascinating testing and diligent reports.

    • B.B. Pelletier Says:

      Feinwerk,

      The 1:16″ twist rate is almost universal in airguns, as it is in .22 long rifle firearms.

      B.B.

      • feinwerk Says:

        What about higher power firearm rifles? Is 1:16 typical for them too?

        • B.B. Pelletier Says:

          feinwerk,

          No, in other firearm calibers the twist rate is set to whatever will stabilizer the bullet that the barrel maker expects the shooter to shoot the most.

          In fact, Feinwerk, you have given me a great idea for a blog on twist rates and why are they different.

          Thanks!

          B.B.

      • Feinwerk Says:

        Ahh, so there is a precedent for some specialized variation in twist rates to suit certain bullets in center-fire arms. Can you tell us more about which rates suit which bullet types?

        • B.B. Pelletier Says:

          Feinwerk,

          Yes. I will be very happy to discuss all the important things I know about rifling twist rates — both from reading and from actual experience. This test is one of those bits of experience that showed me some things I thought I knew before. This test made them clearer. I may have to do several installments to get it all out, but that makes a good report!

          Thanks,

          B.B.

  • /Dave Says:

    BB,

    Nice compilation of info on this report! I can see where we are headed now, but to throw a fly in the ointment, every barrel has its own pellet preference. As the distance increases, I’m wondering if you’ll do a search for each barrel’s “favorite” long distance pellet. This would be done as an addendum after you’re done with the CP’s, of course, since they are the standard for this test.

    And to take a fly out of the ointment,… The 2 DQ barrels are a study by themselves since they are at both ends of the twist spectrum. Any quality questions aside, they both came from the same maker….

    It seems to me that the standard twist is best for the widest choice of range with the broadest variety of pellets. The 1:22 sure seems like it would be a viable choice for a 10 meter gun though! The 1:12 barrel seems to over stabilize the CP’s, letting the pellet precess at longer ranges when used with higher power settings. Perhaps the fat twist barrel would be useful at higher power, long range with a long heavy pellet like a Eun Jin.

    /Dave

  • B.B. Pelletier Says:

    /Dave,

    All good thoughts. I need to finish this test first and then perhaps I can do further investigations.

    B.B.

  • John Says:

    What this test proves to me is that regardless of twist rate, Airforce airguns are all seriously accurate as they prove to be time and time again. When you get down to it, there is not an airgun out there that would be pressed to it’s limit to do what a stock airforce gun can do. I’ve seen “Frankenguns” that could do some serious long range shooting, but take one right out of the box and an airforce gun right out of the box and there is no way “gun B” can out perform that airforce gun. I just proved this again on my own range against Dan’s “Frankengun” that I grew to hate after gutting it for the third time in a day trying to keep it firing for him. (That one is a cobbled old talon that I can’t swap barrels in unless I want to completely gut the gun again.)

  • Joe Says:

    B.B.,
    I read your test results with great interest. One very important thing your test results show is that rifle twist rate is important at high velocity (power setting at 10). Your charts show this effect at 25 yards, when a pellet is over-stabilized and under-stabilized. I’m waiting for your continuation at 50 yards, because the pellets will be at its downward flight. An over-stabilized pellet will be pointing upward as it flies in its downward trajectory toward its target.

    Also, I’m interested in repeating this test when the pellets are moving at nine tenth the speed of sound (1116 fps at sea level = speed of sound), because according to scientists, a plane flies smoothly up to eight tenth the speed of sound, after that it would suddenly encounter a rapid increase in drag.
    Thank You!

  • Matt61 Says:

    Okay by me to pass up the barrel comparison. There are enough variables in this test. If I had supposed that pellets would be optimized at a slower twist rate because spin is less important to them than bullets, than a 1:16 twist would be consistent with that as a rough approximation.

    For graphing, what about using the power setting as the horizontal axis and the various twist rates as the vertical axis. Pick only one pellet. Color code for 10 and 25 yards (red for one and blue for the other for example). If necessary, average the three trials. Some picture should emerge.

    /Dave, that is amazing that your Dad was in the Philippines. I heard that Tommy guns were always in demand so your Dad was lucky to get his choice. Much as I love the M1 Garand, I can see how that would not have been ideal. Your Dad must have some amazing stories to tell.

    We’ve talked about firearms as a source for more airgun shooters, but what about archery. My sister-in-law has made remarkable progress in her attitude towards guns. She formerly hated guns categorically and refused to let my brother go shooting with me and my Dad. However, when the mad sniper brought out his tacticool 22-250, she was handling it with interest. And she admired the archery equipment that I got for my brother and had no problem with us going to shoot. I’d say we’re beginning to hold our own here.

    On that subject there is a question. How do you compare the recurve vs. the longbow design? My understanding is that recurves shoot farther and have less hand shock than long bows. On the other hand, they are less accurate and “smoother shooting.” The reason for both is that the longbow does not contact the bowstring unlike the recurve which does at the two ends which are “refused.” (It should be noted that most longbows have a deflex/reflex design which is a very slight recurve to reduce vibration and handshock but they are still distinct from recurves.) Anyway, the differences between recurves and longbows above make sense from a design point of view. However, I believe the Olympics use recurves as I saw in an astounding demonstration where these finalists were grouping arrows within a few inches at 90 yards. Any difference in accuracy between recurves and longbows looks to be academic. On the other hand, while shooting my brother’s recurve, I noticed that certain shots would go bad for reasons that I could not anticipate. They didn’t feel “smooth.” So, I attributed that to the recurve design and string contact. Anyone have information on these points?

    Matt61

    • Titus Groan Says:

      Hello Matt
      I was ready to start typing an answer to your question on the difference between the English longbow, and the Turkish recurve, and soon realized there was more to your query then just a paragraph of two could cover. So, I strung up my longbow, and my recurve, and had a long look at the two. First of all, what I call my longbow, is not the same as what was used in Henry VIII’s day. When unstrung, the longbow is a long, straight stick, made from a single piece of yew. No arrow shelf or sight window. The front of the bow is curved, like a D. The back, or the part facing you as you shoot, is flat. The longbow was as tall or taller then a man of those days. 72in. would be the average. And this is where the bow gets it’s power. The length of the bow means an average man can draw and shoot a 72in. bow at 50lbs@28in. a lot easier then a 50in. bow at 50lbs@28in. Back in King Henry’s time, every able bodied man was expected to practice with his bow every day. Tournaments would be regularly held so it could be determined who was practicing and who was slacking. The longbow reigned supreme until it met the Turkish recurve. The recurve is shaped in such a way, that when unstrung, many people not familiar with it, will put the string on backwards. I know this, as it happened to me the first time. However, when strung properly, a 50 in. recurve at 50lbs@28in, will draw smoother and shoot further then the longer English bow. The “recurve” of the limbs, gives the bow more “cast”. Something like throwing a spear, and using a spear thrower, to throw the spear. So the recurve was able to shoot further with more accuracy then the longbow. I’m not sure of the names of battles where the two philosophies of archery first met. The recurve proved superior.
      The modern longbow has a deflects /reflex design, as well as a sight window cut out so when the arrow is on the rest, there is a straight line from the string to the arrow rest. This allows for using arrows that are lighter. There is less “bending” side to side, as the arrow is released and travels to it’s target. The modern longbows have a straight front and back, and are usually laminated for strength. These are sometimes referred to as American longbows, or flatbows.
      As to your experience with certain shots going bad for no apparent reason, well, this opens a big can of worms. Like airguns, there are so many things that need to be done consistently every time you shoot, or things go awry. As the saying goes, it is a poor archer/shooter, who blames his equipment. We could talk of finger placement on the string. A relaxed bow arm, and consistent anchor point. There is a long list of culprits that only hours of practice, or a good coach, and hours of practice, will alleviate these problems, and give you the consistency you desire. New archers will typically use their bicep muscles to draw the string instead of squeezing their shoulder blades and back muscles together. As Eugen Herrigel explains in his book, “Zen and the Art of Archery”, the proper release is not something you do. It is like a branch of a tree bending with the weight of accumulating snow, and suddenly shedding the snow as it gets too heavy. This is not a direct quote, as I have lent my copy to a friend, but I have never heard a better example of a proper release or trigger squeeze.
      I hope this answers one or two of your questions. Like airguns, archery is a life long process of learning the subtleties of the sport. B.B. has shown this is true with todays and the dozens of other topics I enjoy so much.
      Caio Titus

      • Wulfraed Says:

        I suspect what you refer to as a Turkish recurve is what I know of as a composite bow. They were a laminate of three materials: horn, wood, and sinew (and being a laminate is why they didn’t do well outside of the drier climates — the glue tended to separate).

        These bows were quite short, and yes, when unstrung the limbs bent over into a C shape as the ends curved away from the archer. However, for a true composite, the strung position may not have had the string contact of a western/modern recurve

        English longbows partly needed the length to avoid shattering the wood when drawn. The limbs don’t have that much flex, compared to composites.

        It’s been too many years but… Modern recurves have a different acceleration curve than a straight longbow; I don’t think the string contact is a factor in accuracy unless one has a poor release that is pushing the string to the side. As I view it, the contact as the tips move forward results in the string moving faster than the average limb motion.

        In contrast, compound (aka: wheel) bows have limbs that barely move… maybe an inch or so during a draw; and even some of that may disappear on bows with really high let-offs (what are common: 35% and 50% let-off? A 60lb hunting bow with 50% let-off drops to only 25lb at full draw as the eccentric pulleys actually let the limbs move back up into untensioned region)

    • Wulfraed Says:

      For graphing, what about using the power setting as the horizontal axis and the various twist rates as the vertical axis. Pick only one pellet. Color code for 10 and 25 yards (red for one and blue for the other for example). If necessary, average the three trials. Some picture should emerge.

      Maybe something like: http://wlfraed.home.netcom.com/TwistTest.png

      Note: I’m still studying the R books I have — IF it worked like I wanted, the pellet types should be the o vs x markers. This is a simple R “pairs” plot in which I excluded the pellet type from the plot. Obviously, some plots are meaningless… There were three twist rates and three power levels for each pellet, so the 3×3 plot at the intersection of Twist and Power is pretty much a given.

      However: Group (size) vs Twist may be interesting, as is Power vs Velocity. I don’t know if Velocity vs Group is meaningful (and again, I’m hoping the o are Premier and x are JSB — I need to actually compare the spreadsheet to the plots to see if the hypothesis is correct).

      • Titus Groan Says:

        Hello Wulfraed
        I must say upon first glance, your graph looked quite daunting. However, it only took 30 seconds before the information you presented became clear. I have always admired folks who were good at correlating information and then presenting it in a way that makes sense to an average person such as I. You are quite gifted my friend.
        Caio Titus

        • Wulfraed Says:

          I’m not the one you should be giving credit to… As I mentioned, this is one of the built-in functions in the R Statistics software package… All I did was reformat the tables into a format R prefers:

          Pellet Twist Power Velocity Distance Group
          Premier 12 0 452 10 0.509
          Premier 12 6 777 10 0.408
          Premier 12 10 846 10 0.281
          JSB Exact 12 0 434 10 0.578
          JSB Exact 12 6 786 10 0.419
          JSB Exact 12 10 830 10 0.286
          Premier 16 0 486 10 0.495
          Premier 16 6 787 10 0.404
          Premier 16 10 854 10 0.247
          JSB Exact 16 0 507 10 0.100
          JSB Exact 16 6 778 10 0.092
          JSB Exact 16 10 823 10 0.299
          Premier 22 0 534 10 0.258
          Premier 22 6 840 10 0.293
          Premier 22 10 854 10 0.288
          JSB Exact 22 0 521 10 0.324
          JSB Exact 22 6 817 10 0.309
          JSB Exact 22 10 815 10 0.530
          Premier 12 0 452 25 0.903
          Premier 12 6 777 25 0.375
          Premier 12 10 846 25 0.753
          JSB Exact 12 0 434 25 1.142
          JSB Exact 12 6 786 25 0.979
          JSB Exact 12 10 830 25 0.944
          Premier 16 0 486 25 0.480
          Premier 16 6 787 25 0.654
          Premier 16 10 854 25 0.329
          JSB Exact 16 0 507 25 0.571
          JSB Exact 16 6 778 25 0.569
          JSB Exact 16 10 823 25 0.359
          Premier 22 0 534 25 0.671
          Premier 22 6 840 25 0.845
          Premier 22 10 854 25 0.082
          JSB Exact 22 0 521 25 1.949
          JSB Exact 22 6 817 25 1.797
          JSB Exact 22 10 815 25 1.172

          (In truth, Twist rate, Power setting, and Distance should be considered as “text” “factors” and not continuous data — just like the Pellet is a “factor” of two values, twist/power is a factor of three values and distance [so far] is a factor of two values)

          Note how there are not separate columns for the different pellets — Instead the distance/power data is duplicated…

          The “pairs” function takes each factor (column) and produces a scatter plot for each pair of factors/continuous data. I excluded the pellet type from the plot and attempted to tell it to use a different plot character for each pellet type [to be confirmed when I take time to match the plot to the spreadsheet].

          It only takes two R commands to produce that plot:

          tt = read.csv(“TwistTest.csv”)
          pairs(tt[,2:6], pch=c(1, 4))

          (Heh, I don’t recall exactly which pch [plot character] set I used…. circles are 0, I think…)

          If interested, consult: http://www.r-project.org/
          R is an open/free package inspired by the S-plus statistics package (which, last time I looked, has been absorbed by some other commercial package with a different focus than pure statistics). There is much overlap, though with Octave (an open/free competitor to Matlab) — but I don’t have much experience with the latter; they are more pure number crunching packages, less analytical*.

          * I sometimes wonder how my college Stats II course would have been if R had been available (confession — as a CompSci major with a /system software/ emphasis, I did NOT take Stats II — the /business software/ emphasis had to take it. Stats II used SPSS [Statistical Package for the Sociological Sciences]… 1978 period)

      • Wulfraed Says:

        Okay… the markers weren’t correct on the plot. Appears that, specifying two markers to be used, resulted in them alternating in the data — but as seen in the listing, there are three entries of Premier followed by three for JSB. I had the choice of trying to sort the data so the pellets alternated, or change the plot command… Was a bit easier to change the plot command — duplicate the markers: pch=c(1, 1, 1, 4, 4, 4)…

        Corrected plot is now at that same URL

  • David H Says:

    One thing I found interesting in todays report is that in two instances the Crosman Premeires had a better group size at 25 yards than at 10 meters with the same barrel and at the same power level. That really flys in the face of reason.

    David H

  • Pete zimmerman Says:

    I AM alive. Not doing well but hoping for a miracle. When las I wrote I was recovering from radition treatment. That’s finished; I really do seem to have licked cancer.

    But in a possibly related development, my kidneys are failing, and I’m groggy a bit of the time and dead tired the rest. I am on transplant lists and have offers of three living kidneys from people who love me. We are praying that one is close enough a match to work.

    I have not pulled a trigger in a literal year. I do hope to try again this coming weekend.

    My best to all my friends here; I’ve missed you.

    Pete

    • Victor Says:

      Pete,

      Good to hear from you. Thanks for the update. We will be praying for you.

      Victor

    • Fred DPRoNJ Says:

      Pete,

      I will say a Mi Sheberahk (pray for healing) for you. No one deserves this type of trouble. Good luck!

      Fred DRPoNJ

    • B.B. Pelletier Says:

      Pete,

      Glad to hear from you. You are in my prayers every day. May this be the beginning of a successful recovery and may your kidney situation be resolved.

      You don’t have to pull triggers to be with us. Just drop us a note every now and then and know that we all think of you a lot.

      B.B.

  • Gunfun1 Says:

    Why and how did the factory 1 twist of revolution in 16″ barrel get chosen by Air Force ?
    And it looks like it just so happens to average out to be the best so far out of them all.
    I believe that it was mentioned that it was a 12″ barrel if I remember right.

    From what I have seen on some firearms is that (some) of the longer range sniper rifles tend to have longer barrels. I know we are talking about different grn. projectiles and velocity’s for firearms verses airguns.

    But what do you think the results would be if you used the same power settings and pellets and 1:16 twist, but with a longer barrel ?

    Just curious if you have attempted that test yet.

    • B.B. Pelletier Says:

      Gunfun1,

      AirForce chose to retain the same rifling twist that every other airgun manufacturer in the world uses. 1:16″ is nearly universal.

      You have asked way more than I think you meant to. It would take a small book to answer you properly — assuming that you know nothing about twist rates or exterior ballistics.

      I will begin tomorrow.

      B.B.

      • Gunfun1 Says:

        All I want to know is if you have tested a longer barrel keeping the power level and pellet the same. Not asking about writing a book.

        Replace barrel, shoot and see what happens.

        And I’m sure you heard the saying about assuming.

        Remember that’s what I have been involved with at work for too many years. When I ask a question its because I’m sure that some point in time you experienced it in some form or another. And I really don’t feel like searching back through the archives when I’m sure you have it somewhere in your memory.

        And when I ask a question it is to make somebody think.

        • twotalon Says:

          GF1….

          I have done that. I swapped in the 24″ barrel in place of the 18″ barrel in my Talondor without changing a thing else. Power went way up, but shot count was cut in half.

          twotalon

          • Gunfun1 Says:

            Did it help accuracy also ?

            • twotalon Says:

              GF1…

              That’s a yes/no/maybe kinda thing. The 18″ is a good shooter since I did a recrown, and the 24″ is a super shooter in the first place. Maybe B.B. remembers me talking about my purple barrel a long time ago.
              But we get back to the thing nobody wants to hear about….
              They are different barrels in the first place, no matter what the length. You can’t make any simple rules to use in all situations.

              twotalon

        • B.B. Pelletier Says:

          Gunfun1,

          Sure, I have done that many times here on the blog. Same gun (this one, in fact) and two different barrel lengths 12 and 24.

          B.B.

  • Gunfun1 Says:

    I have been trying to find some different barrels for my .177 Marauder. and still keep the shroud working.

    That’s kind of my test gun. I would like to go to a shorter barrel in it then add more of the factory cup spacers. I still want the accuracy and hope to make the gun even quieter.

    I know Mike T. that makes the muzzle brakes and shrouds for air guns. So I could do that but I don’t want to add anything to the outside of the gun.

    So that’s why I have been watching the report to see if anybody did something similar before I start investing time and money.

    So thanks again twotalon.

    • B.B. Pelletier Says:

      Gunfun1,

      Are you asking for a test with a 12, 18 and 24-inch barrel in the same powerplant? I can probably do that for you, and it might be an interesting test for many of the newer readers.

      I would test velocity and accuracy7 I’d want to do it 25 yards, because getting a good day to shoot 50 yards is iffy, here in Texas.

      • Gunfun1 Says:

        Yes exactly. That would be great. I was just getting ready to order a barrel and the spacers from Crosman for my .177 Marauder. And the results would be interesting.

        Don’t know why I called them cup spacers above. They are the baffles.

        But you posted the #8 accuracy report so I was holding off to see what the report would bring. Then you did this #9 report.

        So the comment that interested me the most was (twotalon’s) comment about the velocity going up and shot count going down when he went to the longer barrel.

        The reason being I’m going to go the opposite way on my Marauder so I can get more baffles in the shroud. I’m going to add about 3 more baffles. And I haven’t measured exactly how much that is yet. But I was going to take the barrel to work and cut it to the correct length and re-crown it.

        So if it works out in my case of going shorter than my factory length. Hopefully my results will be the opposite of what (twotalon’s) results of going to a longer barrel.
        If I get more shots per fill and end up with a little less power it will be great because I can always go and re-tune the guns power back up if needed.

        So I am going to order my parts tomorrow. And if the above results work out good. And the gun still ends up being accurate enough for my purpose I will be happy.

        But yes BB I will be interested in your results. As always. So please do if you can. Thanks.

        • twotalon Says:

          GF1…

          Did I confuse you a little ?
          You are working on a Marauder, and I have a Talon running on a Condor power plant. I have no idea how Crosman has got the firing mechanism rigged up on your rifle.
          I have my Talon adjusted to run a very nice curve at the power level that I wanted. Changing the barrel length screws up the tuning. The valve has back pressure on it longer with the longer barrel, so it will stay open longer and sucks more air. I did not want to bother with a re-tune to try getting the power level back to the same as I had with the 18″ with a nice curve. If I could have pulled that off, I could have gotten the same power with more shots (in theory).

          twotalon

          • Gunfun1 Says:

            twotalon.
            No I understood what you meant. I guess I’m mostly trying to get my gun more quiet. And I hope that accuracy will still remain good. Shot count don’t matter that much to me. And if power output of the fps drops off some it wont bother me either. I just know from the Marauder design that I would be able to play with power output. But again thanks definitely good information.

      • Gunfun1 Says:

        And of course all 3 different length barrels the same twist rate.

  • -Juhani- Says:

    Watch this:

    http://www.youtube.com/watch?v=QFou_4VqLBY

    It is a same classic thing again, just with a new interesting presentation: stay under 280 m/s with those .177 pellets …

  • Bret H. Silva Says:

    Ruger’s factory barrels don’t have a good reputation for shooting accurately, but our tests suggest that’s a bad rap. The factory tube shot most ammo groups in the 0.6-inch range, only slightly more than the expensive Briley model. Syl Wylie, Ruger’s marketing director, said that in developing the company’s new 10/22 T heavy-barrel target rifle, Ruger engineers tested several aftermarket barrels to see how well they shot in comparison to the standard-contour factory barrel. “We found out that there wasn’t as much difference as some people think,” Wylie said. Moreover, the comparatively loose chamber size didn’t cause a single ammo to malfunction—a recurring problem with the choked-down aftermarket chambers.

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