How does rifling twist rate affect velocity and/or accuracy? Part 11

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

Part 1
Part 2
Part 3
Part 4
Part 5
Part 6
Part 7
Part 8
Part 9
Part 10

Continuing our look at the 3 different twist-rates, today I’ll shoot the factory Lothar Walther barrel at 50 yards. The factory barrel has a 1:16″ twist rate that has become ubiquitous for airguns and is the very thing this test is designed to examine. Last time we looked at how the 1:22″ twist barrel did at 50 yards, with 2 different pellets fired at power levels 6 and 10. Today, we’ll see the same thing with the factory barrel.

This test was performed yesterday, and the range conditions were perfect. There wasn’t a breath of air to be felt for most of the shooting session, and only an occasional puff of air later on in the morning after I swapped barrels for the final test. I’ll report on that set of results in the next report. Today is devoted to the factory barrel.

The AirForce Talon SS shoots with a fill of 3,000 psi, so before the test I filled the reservoir. Twenty shots would be fired at power setting 10 and another 20 at power setting 6, plus one shot at the start of the test and when the power wheel was changed. I haven’t reported that fact until now, but it’s my standard practice when shooting at 50 yards with a Talon SS.

Valve needs to be exercised
I have learned that the Talon SS valve needs to be fired one time following power adjustments to get it set at the new power level. The first shot will usually be like the gun was on the previous power setting, but the second shot will be solidly at the new setting; so I always take one shot to set the valve with every fill and at every power change.

Talon SS Tom at bench

Shooting off the bench at 50 yards on a perfect day with the Talon SS was enjoyable.

Power setting 10
I started with power setting 10; so when it was time to shoot on power setting 6, the reservoir would have less than the full fill pressure. That way, I knew the gun would be right in the middle of the power curve.

Crosman Premiers
The first pellets I tested were 14.3-grain Crosman Premiers. Because the groups had dropped so far below the aim point in the previous test with the 1:22″ barrel, I dialed up the elevation several clicks for this test. I was hoping to hit the bullseye with the new sight setting, but Premiers on power setting 10 still dropped about 3.50 inches at 50 yards. Ten Crosman Premiers went into a group measuring 1.567 inches between centers. While that’s on the large side for a Talon SS in my experience, it was still a very round group.

Talon SS Premiers 50 yards 10 power

At 50 yards, 10 Crosman Premiers went into this round group, which measures 1.567 inches between centers when the power was set to 10.

JSB Exact Jumbo
Next, I switched pellets to 15.9-grain JSB Exact Jumbo and shot another group of 10. This was also at power setting 10, so the gun’s valve did not need to be awakened. These pellets hit about 2.50 inches below the aim point, so they landed higher than Premiers at the same sight setting. This time, the 10 pellets went into 1.283 inches — a much better group than the Premiers, though there was a hint of vertical elongation to this group.

Talon SS JSB Exact Heavy 50 yards10 power

Ten JSB Exact Jumbo pellets made this 1.283-inch group at 50 yards on power setting 10. This group is slightly vertical.

The difference between the Premier group and the JSB group was evident through the scope without walking down to the target. Clearly this barrel likes the JSB pellet better. What did surprise me was that even on this perfect day I did not shoot a group smaller than one inch. I’ve done that so many times in the past that I sort of expected it — especially on such a perfect day. Well, it just demonstrates the difficulty of shooting such tight 10-shot groups at this distance.

Now, I cranked the power wheel down to 6 and shot both pellets, again. The first shot settled the valve at this new setting, then the groups began in earnest. JSBs went first since I’d just finished shooting them at power setting 10.

This time, 10 JSB pellets went into a group that measured 1.53 inches between centers. It was larger than the same pellets on power setting 10, but smaller than the Premiers on setting 10. The group is fairly round, though most of the shots are clustered on the right side.

Talon SS JSB Exact Heavy 50 yards 6 power

Ten JSB Exact Jumbo pellets made this 1.53-inch group at 50 yards on power setting 6. Notice that 7 of the 10 pellets landed on the right side of the group.

The final group was 10 Premiers fired on power setting 6. They made a group measuring 1.261 inches, which is the best group of the 4 shot with this barrel. It’s more open than the best group of JSB pellets, but the overall measurement places it at the top of the ladder.

Talon SS Premiers 50 yards 6 power
Ten Crosman Premiers on power setting 6 made the best group of the day, measuring 1.261 inches between centers.

Did you notice that the pellets crossed in their performance relative to power, with JSBs doing best on power setting 10, while Premiers did best on power setting 6? I wouldn’t make too much of that because we don’t have enough data to make any conclusions, but it is interesting. In the macro, it does appear that Premiers prefer lower power while JSBs prefer higher power — at least at 50 yards.

I have to admit that I was surprised not to see even one group that measured less than one inch. I’ve shot so many small groups with this rifle that I expected it this time, at least with one of the four groups that were produced.

Final note
In the next report, which is the same shooting done with the 1:12″ twist, there will be a surprising result. So, there’s still more to come.

40 thoughts on “How does rifling twist rate affect velocity and/or accuracy? Part 11

  1. Sometimes you just can’t do it.

    Every air rifle and air pistol at the Olympics was capable of shooting a “perfect” score. Likely, every competitor there had shot numerous “perfect” scores. How many “perfect” scores were shot?

    I know the information is in my head somewhere, but at 4:30 AM, it is not wanting to surface in the mire of my mind. What does a vertical group typically indicate?


    • RR,

      A vertical group could be a wide variation in velocity, or it could be a spiraling pellet — again at different velocities — or it could be a loose barrel.

      In this case, I don’t think it is anything.

      B.B.


      • I was shooting my new sproinger, a Ruger Air Hawk, yesterday at 25 yards and one of my groups was spread vertically. I have the trigger adjusted to where it is not too bad, almost as nice as my CFX was. Now if I can just relearn to shoot a sproinger, and put a decent scope on it, I think I may get some surprising groups out of this thing.

        Some days, even if everything else is “perfect”, you just cannot seem to do it.


  2. I’m also kind of surprised that you didn’t get sub-1″ groups with the factory barrel with this legendary gun! That’s not to say that I can do any better, if be pretty happy with those results. After all, it’s a freakin’ airgun at 50 yds! That’s more rimfire range than anything (at least I would grab a rimfire for work at this range if possible…)…

    /Dave


    • /Dave,

      My Ruger 10/22 on which I have spent a lot of money cannot shoot any better that the Talon SS in this test — unless I attach the 20″ bull barrel.

      These are good groups, but the Talon SS is capable of much better groups than this. I guess I have been shooting the SS with the 24″ barrel for so long that I forgot how it performs with the stock 12″ barrel.

      Oh, well — the test is not over yet.

      B.B.


      • It’s not over ’til its over…. I was actually thinking more along the lines of terminal performance in terms of energy delivered in my comment. I realize that pcp’s are better, but being somewhat older, I still think of a .22 cal airgun as a “backyard gun” versus a rimfire being a field gun. I didn’t explain myself very well though…

        /Dave


  3. B.B.

    My 12″ .22 barrel is not as good at 50-60 as the .177 is. Have no idea just why. Both barrels lead quickly with CP if not lubed. In fact I think the .177 is also better at 25 .

    Could be just luck of the draw, but could be other reasons.

    twotalon


    • TT,

      Well, that’s good to know. Like I said, I have had that 24″ barrel in the SS for so many years that I lost track of what it could do. When I tested them at AirForce it was always at 23 yards, which was the longest distance I could get in the old factory.

      B.B.


      • B.B.

        One other thing that could be an accident…

        With my talon, the 24″ seems easier to shoot than the 18″ . May be sheer weight of the barrel or the inherently lower frequency vibration patterns in the 24″ .

        twotalon


  4. I have no idea why but I find that I get tighter groups when there is a lite breeze from one direction than when it appears to be dead still. This phenomena has proven itself to me not only with airguns but with my best .22 rifle, a Rem 40XB and using its favorite RWS ammo. I keep detailed records for the .22 and find over and over that the groups with a breeze are .1 to .2 inches smaller than those shot in still conditions. Of course all that changes if the wind gets gusty or over 5 mph.


    • Sam,

      Is this the Remington 40X that is suppose to be tunable for ammo by adjusting two screws on each side of the front of the stock?

      Thanks,
      Victor


      • Victor,

        That’s the one. When you see how soft the springs are that push on the buttons on either side of a massive barrel, its hard to believe that they could really do anything. And really I have only been able to see .05″ difference when tuning the best ammo. With less than the best it does not appear to have any effect.


        • Sam,

          Have you tried;

          Wolf Match Extra, Wolf Match Target,
          Eley Red (Tenex), Eley Black (Match),
          Lapua Midas+, or Lapua Center-X?

          Victor


          • Victor,

            I have tried all of them except Lapua Center-X. The old Eley Tenex before they changed the nose shape was the best, now the RWS Match seems to be the best but the Wolf Match Extra is so close and so much cheaper that its what I use for practice and casual matches. Of course lately with the shortage and me down to my last 5000 rnds of wolf I dont shoot them much either.


        • Sam,

          I’ve read that the springs don’t seem to do anything, and so the best performance is achieved by adjusting them to minimal or no tension. Of course, I read that in another blog, and over the years I’ve learned not to trust much of what is said in most of the other blogs.

          Victor



      • B.B.
        I know, I cant explain it either. I know when I was shooting the CMP matches that on a very still day the mirage at 300 and 600 yds would cause the targets to dance around and a lite breeze would sweep it away, it was also a good way to determine the wind speed and direction. I have never really noticed it over grass at 50 yds but wonder if it could have some effect.


        • I agree with your preposterous assertion :). One, I think your mention of mirage is important — a little movement in the form of a steady breeze minimizes that. Also, there is no such thing as a still day — even if there were no air currents, there will be thermal regions, ala updrafts, but there is always wind somewhere — better to be able to guage it than be oblivious to random variations down range.

          So, I think it is partly ballistic, but mostly visual. I’ll go with that since I’ve found that offhand matches even at 50 yards with open sights show the same pattern — kind of a sweet spot where the breeze is detectable but not a “wind” and even better if the sun is under some light cloud cover, though not to the point of completely overcast. Wind is not big issue with my .50 until it gets “brisk” at 50 yards, so I think consistency of sight picture and range condition is biggest factor. Of course, my flintlock has a 42 inch barrel that can be and has been blown around in bad wind conditions, adding to the fun.


          • BG,

            I know it sounded strange but my BR50 scores are always better with a little breeze. I didnt really realize it until I started entering all weather conditions and scores into an excel spreadsheet and when I sorted on group size and score I noted that 9 out of 10 of the top scores were with a breeze.


      • That don’t commend itself to reason. But perhaps the perception of a light breeze means that the wind is at least constant compared to the lack of any perceived breeze which could be hiding vortexes and variations that are too slight for us to detect but which can still affect the flight of a pellet.

        Matt61


      • B.B.,

        Preposterous is what I thought, however, I’m open to the idea that it’s not impossible.

        My first thought is that Sam has made this observation because maybe he tries harder in wind, even when there’s just a little wind. Concentration is a huge factor when trying to shoot for consistency.

        [Wild Theory] On the other hand, suppose that a little wind affects spin (I don’t know that it does). But if it does, then this small amount of wind could be providing a sort of tuning. I’m just throwing this out, but consider this specific blog series. Sometimes theory and observation are at odds with each other, so another theory (or an expanded theory) is in order.

        Victor


  5. I am still amazed at how large of an effect pellets have on accuracy. My recent purchase of an Airforce Edge prompted me to try several different pellets after being disappointed in the RWS Hobby’s and Crosman premier wadcutters I had on hand that were producing .5″ groupings over 5 shots.

    The three new pellets (I tried) and there results shooting 5 pellet groups at 10 meters (no wind) from a sitting position resting the gun on my knee were as follows:

    RWS R-10 match – 2 groups measuring .201 and .312 center to center.
    H&N Finale Match pistol – 2 groups measuring .162 and .181 center to center
    H&N Match pistol – 1 group measuring .513. This group was too wide to warrant a second 5 shot group.

    Obviously being that the gun isn’t clamped in a vice, the results aren’t perfect but its clear that the
    R-10′s and Finale match pistol are acceptable pellets for this gun.


  6. B.B.

    Well, that’s unpredictable – I mean I made some estimations, but they were absolutely not like that. Let’s wait for pt 12.

    I received my conversion kit for FWB C62. Air pressure regulator is set to 110 bar and reservoir pressure is 300. Everything seems to be fine when assembled and filled up, on Saturday I plan to fine-tune it to 16 J, zero it and try to make something at 50 m.

    duskwight


    • duskwight,

      It fooled me, too. But wait until you see what’s next!

      Good deal on the FWB C62. To get 16J from a short barrel like that is a real trick. Long valve open time and large oriface, I suppose?

      B.B.


      • B.B.

        Funny, but no drilling.
        Just increased input pressure (60 with CO2 to 110 with HPA) and some tricks with striker screw in/out – it might actually be turned “colder” than maximum setting for CO2 to some shorter open time. That’s just calculations, practice will show the truth. Alas, the barrel is 425 mm, not too short, but of course I’d like some longer stuff. Maybe I’ll put there a whole 605 mm blank from LW or CZ.

        duskwight


  7. BB thanks for throwing the info in there about the extra shot that you take when you adjust the power wheel. Twotalon has mentioned this before also.
    My Talon SS is supposed to be here today. Cant wait. But I might have some questions about the operation of the gun in the future.
    And what I’m getting from what I read above the longer barrels are more accurate?



      • I use the Hawke 2.5-10 X 44 AO Varmint scope on my 1720T and Marauder pistol.
        And both Marauder rifles have the 3-12X44 AO Varmint scope. Also the Talon SS I got today.
        Great scopes. No particular reason about what scope it was. Just interested in knowing.

        But I do have two questions though.
        Do you shoot at the highest power magnification the scope has when you shoot or do you dail it down?
        And what height scope rings are you using on Your Talon SS?
        I put the tallest ones I have on my Talon SS (about one and a half inches from the receiver grooves to the center of the scope) Seems like I need about a 1/8 inch more taller for the gun to be comfortable when I hold it.


    • GF1…

      No two barrels are the same no matter what the length. They could be super good or super bad.
      You also have a change in power plant efficiency. They also change the weight and balance.
      There will be a velocity change, but we don’t know what the pellets would think about that.
      Would be a bad idea to jump to conclusions and make any blanket rules . You get surprised a lot when you do that.

      Let’s just say that “this is what happened with THIS barrel and THAT barrel” and leave it at that.

      twotalon


      • Well I know that. It was just interesting to me that the barrel performed the way it did. And there is always those strange things that happen.

        BB mentioned above about shooting his best group in the rain with his AR. I have done the same with my air guns. Just didn’t mention it.

        But as it goes anything could be possible.

        And also the Talon SS I just got with the standard tank did not come with new Sound Loc Kit in it (baffles). I shot it with out them and it wasn’t to bad on how loud it was. Went ahead and put the kit in and it definitely quieted the gun down.

        I just got to get taller scope mounts or the scope riser spacer and I will be set.


        • GF1

          You need high mounts at least. Another way is a tri-rail or other riser block (one piece) to get the scope up a ways. A level helps. I have the clamp on ones mounted on the top groove of the frame a little way in front of the scope. If you get the level, get in the habit of checking it before you shoot. These rifles are easy to be badly canted because of the ergonomics.

          twotalon


          • Twotalon. I totally know what you mean about cant. Learned about keeping the scope cross hairs level long ago. Amazing all the things you have to do to get things in place at the right time when you make a shot.

            And yes took some messing around to get the adjustable shoulder stock where I felt comfortable when I held the gun.

            But I can tell I’m going to like the Talon SS. It compares to my 1720T with the 1399 shoulder stock in to many ways.
            If I want to make sure I hit something with the guns I have, the 1720T is it. And I have it tuned for more power than what it had when it came from the factory. The Talon SS is the same as far as accuracy goes and a little stronger than the 1720T.



  8. Edith, on the subject of pepper spray, have you seen the Steven Seagal movie where he is a Navy Seal disguised as a cook who ends up fighting renegade mercenaries on a train? To get the juices of the audience flowing the unnaturally blond Doc Savage type head mercenary grabs hold of Seagal’s charming niece who happens to be on the train. She gives him a point blank shot of pepper spray to the face with a unit dangling from a chain around her neck. He looks at her without reaction. Then he takes the unit from her hands, gives himself a couple shots down his open mouth and says, “Pepper spray. For civilians. Clear out the sinuses.” Later when fighting Seagal in a death battle with knives, Seagal slashes the guy’s snappy leather coat. That gets his attention and he exclaims, “You’re messing with my coat!” The guy is really crazy…

    You’re the person on the spot! Did you not say that if you had your way, you would be playing tennis all day long? It turns out that my rather low-budget athletic club has a backboard for hitting tennis balls that I first tried out the other night. I can see your point. This is great! Why aren’t you playing tennis all the time? I always kind of sucked at tennis in the few times I tried it. But I think part of the problem is that competition does not help me to learn like most people. I find it distracting in my bloodlust to triumph. My learning is much more efficient when I can concentrate on what I’m doing by myself. So, now my model is the great Monica Seles, my favorite tennis player of all time. The word is that she would have been the greatest ever. She had the number of Steffi Graff, now considered the greatest ever. But some unreconstructed Nazi stabbed Monica in an effort to preserve German superiority (and was never punished). Monica recovered from the near fatal physical wound, but she cracked mentally and was never the same again–although she did cover herself with glory as an exceptionally class person. Anyway, what I want to imitate is her training method in Belgrade where she hit a brick wall with a tennis ball for hours and hours. With this preparation, she gave a demonstration in her pre-teen years of running back and forth on the tennis court at full speed smacking cross-court shots with incredible power into tiny target areas.

    This is also another chance to see if my more improved, mature self can make up for yet another area of failure in my early years. It didn’t start to well with me missing the ball and getting my footwork tangled up. But then I made two very important discoveries. The first was not to hit so hard. Rather than socking the ball as hard as I could, I stepped up closer and worked on hitting lightly enough so that I could make the next shot. It was all about control, and I did better. I consider this analogous to shooting where one starts the marksmanship at a very close distance and then backs up in steps as the ability improves. The next discovery was not to pause my hand at the end of each shot and then work frantically to get into position for the next shot when the rebounding ball was almost on top of me. The voice of an old coach from years ago that I thought I had forgotten came back to me telling me that I shouldn’t wait for the ball but should be pulling my hand back in preparation right away. So, I began flourishing the racquet about, moving from one swing into another. This is similar to a principle of Tai Chi where a master said that what is alive is moving; only what is dead is still. And in shooting, it reminded me of follow-through and more generally where you spread the shot over a whole technique rather than sniping and jerking the trigger. Anyway, it worked. It felt a little weird, but sure enough I found myself in position and was able to put my body into the shots more effectively. Those airgun analogies are popping up everywhere.

    So, what’s the next step to tennis mastery? Any shooting analogies would have extra appeal, but I’m open to anything.

    Derrick and Vince, are you out there? I’m having a heck of a time resealing my Daisy 747 and have questions for you. Can you email me at gufgo24@yahoo.com?

    Matt61


    • Matt61,

      I have never seen a Steven Seagal movie. I can’t stand him…and that’s without ever having seen him act!

      I haven’t played tennis in a long time. I have a tennis practice set up on the back porch and used to use it daily. I’d name the ball the person who irritated me the most that day. As I hit the ball, I would let out all sorts of anger. It was very therapeutic :-)

      It would be nice to be able to play tennis all day long, but I don’t see that happening anytime soon. Right now, I’d be real happy to sleep for 3 months :-)

      Edith


    • Since it is on a train, it would be “Under Siege 2″ (“Under Siege” being the aircraft carrier movie)

      Pepper spray comes in different grades — sometimes determined by individual state laws. Confusingly, California requires (or did) a formal training session and licensing for Mace and variants — but pepper spray became an uncontrolled alternative.

      Hmmm, based on http://www.misdefenseproducts.com/Pepper-Spray-Laws-Restrictions-sp-6.html even regular tear gas has now become unlicensed (but no one tends to carry it any more). OC (pepper), CS and CN… But limited 2.5oz bottles. MI appears to allow up to 10% OC but limited to 1.5oz (so I have a few illegal CA canisters around… blast… Bad enough my CA legal “stun gun” [contact type, not Taser projectile] needs a CCS in MI).

      I vaguely recall at one time that OC sprays were limited to 3-5% (making “bear spray” illegal in that area).


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