Pellet velocity versus accuracy test: Part 9

by B.B. Pelletier

Announcement: Joel Cole is this week’s winner of Pyramyd Air’s Big Shot of the Week on their facebook page. He’ll receive a $50 Pyramyd Air gift card.

Joel’s winning photo is of his niece, Paysen. He was teaching her to shoot a Crosman 66 over Thanksgiving weekend.

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

Today, we’ll complete the testing of the four pellets at four different velocities in the Whiscombe rifle. The premise of this test has been to explore the effects of velocity on accuracy by shooting the same pellets in the same pellet rifle at four differing velocities. I will make today’s report and comment on how the test went, but this will not be the final installment of this test. There will be at least one more summary report that puts all the data into perspective. And if there are side issues to explore, maybe there will be more reports.

At this point, I think I know what I’m going to find when I look at all the data, but there have certainly been a few surprises in this test. And the surprises continue in today’s report. Let’s get right to it.

Beeman Devastators
This time, the Beeman Devastators were averaging 772 f.p.s. Since this is a very lightweight lead pellet, at just 7.1 grains, I would have thought this velocity would be about as ideal as it gets. The pellets thought otherwise. Ten shots went into a 25-yard group that measured 1.073 inches between centers. You’ll have no problem counting all 10 shots, because none of them seemed to want to go to the same place.

However, I do want to draw your attention to the upper right portion of the group. There are 5 holes in a much smaller group measuring 0.399 inches. This is what the best 5 out of 10 shots looks like, and it’s a temptation to say that this is what the rifle/pellet can do. Think not? Well, in a national magazine, a popular gun writer who traditionally shows three-shot groups when talking about accuracy, recently published an article about .22 rimfires in which all the groups were 5 shots — very uncharacteristic for him. But when he reported the group sizes, he twice mentioned the size of 4 out of the 5 shots in those groups! In other words, he couldn’t resist the temptation to make the gun sound better than it really was — even when the evidence was right out in the open. That’s why I most often shoot 10-shot groups.


Beeman Devastators did not stay together this time. This group measures 1.073 inches between the two farthest centers. But look at the much smaller group of 5 in the right-hand corner. They’re both legitimate and a fraud at the same time. They were legitimately shot by the rifle in this test, yet they do not represent the true accuracy of the rifle at 25 yards at this velocity.

Crosman Premier lites
Next, I shot a group of Crosman Premier lites. They did just the opposite of the Devastators — grouping the best they did out of all four tests. The group measures 0.593 inches between centers. That says a lot for this pellet, but perhaps not everything. The velocity at which they traveled was an average of 732 f.p.s. Is it the velocity or something else that makes them so accurate? We shall just have to wait and see.


Premier lites turned in their smallest 25-yard group of the 4 velocity tests. It measures 0.593 inches between centers.

All shooting was done with care
Lest you think I relaxed at any time during this test, I assure you I did not. Each shot was fired with the same care as all the others. The bubble level was consulted each time just before the shot was taken. I now have the trigger breaking at less than 8 oz., so it’s perfection. I’ve even concentrated on my hold to make it as much the same from shot-to-shot as I possibly could.

Beeman Kodiaks
Next up were the Beeman Kodiaks. These were the pellets that had proved to be the most accurate up to this point in the test. This time, however, they opened up to 0.864 inches between centers. You can see that 8 of the 10 shots are in a much tighter group, but let’s not go there yet. The group you see represents how well these pellets did at an average velocity of 658 f.p.s.


Until this time, Beeman Kodiaks had been the most accurate pellets. This time, they slipped to second place, printing a 25-yard group that measures 0.864 inches.

Eun Jin
We have long since passed the point at which the 16.1-grain Eun Jin super-heavyweight pellets are accurate; but just as the United Nations continues to grant its chairmanship to members of the smallest third-world countries, so we continue to shoot this pellet with each test — pretending that is has some part to play. Last time, Eun Jins printed some two-plus inches below the aim point. This time, with the velocity averaging 501 f.p.s., they dropped 6-3/8 inches! They were so low that I had to reorient a target to see them print on the paper.

The group measured 1.724 inches between centers. That’s larger than last time.


Ten Eun Jin pellets dropped more than 6 inches below the point of aim and made this 1.724-inch group.

The results
Like I said in the beginning, I’ll look at today’s results right now, but there will be another report dedicated to the entire test. I want to know what you readers think about this, because a lot of what I do ultimately comes from you.

What I see in today’s results sort of implies that accuracy falls off at lower velocities. Now, I don’t happen to believe that’s the case; but except for the Premier lites, that’s exactly what happened today. That suggests that something else is causing the larger groups. Perhaps vibration? Maybe that needs to be explored.

Looking at the Beeman Kodiak group, and to a lesser extent the Premier lite group, it seems like pellet selection might improve these two groups significantly. I shot all the pellets exactly the way they came from the tin or box. No special sorting technique was used. Would accuracy have improved if I had weighed these pellets and examined them critically before shooting? That’s a question so intriguing that I’m almost compelled to test it next.

On the other hand, no weighing or sorting will improve the groups made by the Beeman Devastators or the Eun Jins that much. They’re just what they are, as the openness of their groups suggest.

If I didn’t have a lot of experience shooting pellets at lower velocities, I might be tempted to make up some sort of explanation as to why they did so poorly. But I’ve shot other slower air rifles that exhibited excellent groups at 25 yards, so it seems like it must be something else. That’s where the thought of vibration comes in. With the Whiscombe, I can alter the vibration nodes with the Harmonic Optizmized Tuning System (HOTS).

That makes me think of something else. You know how we always say that to find the best pellet for a given gun you have to try them all? Maybe what you’re doing is finding the pellet that responds best to the way the airgun vibrates!

You tell me what you think I should do next. I won’t promise to do it all, but I will read with great interest what you have to say.

119 thoughts on “Pellet velocity versus accuracy test: Part 9

  1. Good evening B.B. This has been an exhaustive test A number of conclusions can be made now. Thats a lot of pellets to shoot for one. And with your Whiscombe,having to pump it twice each time is double the number I pump with my Weihrauchs. Being limited to 500fps and 4.2 ft.lbs, I can agree with you on grouping well with slower velocities. This summer I was able to lengthen my outdoor range from 20 meters to 24 meters. Four meters do make a difference at lower power too. Using JSB Exact RS pellets in .177 cal, and 7.33gr., I was able to make 1/2 in. groups with regularity using my HW97. Bench rested on a Caldwell Rock, Jr. I have a Hawke 4x12x50 scope and use the 12 power. This is my favourite rifle-scope in my arsenal. Thank you again for your diligence and patience shooting 10 shot groups. I know for me, I would start off with 10, but would make some excuse to use 8 then 6 and 5. I keep having to ask myself “why are you rushing?” “Stop rushing!!”
    Titus


    • Titus,

      It’s worse than that! The JW-75 I have needs three cocking strokes to make each shot ready!

      Yes, it was a lot of shooting but now there is a pile of data to be examined, and possibly followed up. It was worth it.

      B.B,.


  2. B.B.

    Cute girl. Nothing like a cute girl with a gun. Much better than a big, burly, seedy looking redneck with a gun. PA should give the gift certificate to HER !

    The test…
    What we were looking for was velocity vs. accuracy with different pellets, right? Some of the things you came up with make sense, and some do not. There are gremlins at work here.
    I notice that most of the groups today look like they want to string out in various directions, forming funny shaped groups. Something going on that may be a very complex interaction between several things……

    You are restricting the power plant to change velocity. Not running it at the max efficiency possible. That extra energy has to go somewhere. Usually ends up in vibration.

    Barrels all vibrate anyway, and what point in the vibration pattern does the pellet exit the muzzle? That changes with velocity.

    Then the pellet itself. We have both drag and gyroscopic forces interacting. That changes with velocity.

    What makes sense with one pellet shot at different velocities may not make sense with another for some reason (or combination of reasons) that is overlooked.

    I don’t see how you can come up with something that is set in stone, because physics wants to kick your butt.

    twotalon



    • Twotalon,

      Fantastic point about extra vibration when reducing Whiscombe’s energy output. It is amazing how many things change in the ballistics model when only changing “one” thing. This is no doubt this is why ballistics is such a baffling problem.

      I do wonder how the same experiment would turn out with a PCP.

      I’d be curious what would happen with a smooth-bore PCP at the same muzzle velocities too.

      In my mind a good experiment either answers the question, or raises all sorts of points that would need to be considered in following experiments. This experiment strikes me as the latter.

      Herb


      • Herb & twotalon,

        When I read comments like this, I often find myself amazed that airguns can hit the broad side of a barn. So many things to consider!

        The first company that produces a reasonably priced springer that delivers magnum speed that requires no special hold and is deadly accurate will have a gold mine on their hands.

        Edith


        • Edith….
          No kidding !
          Let’s see now…if you can kill a pig with nerf pellets at close range, what could you do with a .22 or bigger? Moose at 200 yds?

          twotalon


        • If my understanding of .010th of what has been discussed under this thread, I would say Gamo has come close with that Big Cat. I mean, if I recall, it didn’t group that well (or was it the Whisper?). Anyway, my suspicion is that if one was to take a Big Cat, or any one of the lower priced magnum springers and made a tuning screw to put varied pressure on the bbl it could eliminate the effect of vibration on the pellet. Admittedly, the variables of so many different pellets vs. screw pressure an the bbl vs. weather boggles my simple mind and I’d get lost in experimentville.

          ka


          • KA,

            Dennis Quackenbush and I did such a test back in the ’90s. He made a super-heavy adjustable muzzle weight for a Beeman Kodiak rifle and I demonstrated that you could tune the vibration.

            Tom Gore (Vortek) then brought out a commercial version of the adjustable brake and you could hear the crickets chirp. The customers stayed away in droves!

            Maybe this time somebody will listen?

            B.B.


            • BB,

              I wonder… If a ‘cheap’ spring piston gun costs say, $200 – $300 and the adjustable muzzle weight/compensator is $?, are we over the $400 – $500 mark? That would justify going to a better gun for me. Sounds like a great item to have though. Not convinced it would change the poor relationship between my CFX and I. I was thinking more in the lines of a barrel band type of thing that would not only ad varying degrees of pressure to the barrel from the stock, but possibly move forward as well. I read sometime ago on some bench rest centerfire shooters doing this by inserting a threaded bung in the stock and adding a stainless machine screw that can be adjusted with a screwdriver as needed. Not sure how to go about testing such a device. Making and mounting one, maybe…

              ka


              • KA,

                I think underlever vibration patterns are more complex than those of a breakbarrel. That’s why, for the most part, the underlever is less sensitive to which pellet is used, and often why it is more accurate. But as for what can be done to attenuate the vibration patterns of an underlever, I think any device that could do it will be much larger than the adjustable brake seen on breakbarrels, because it has to have so much more mass.

                That’s just what I think, mind you. I have no proof.

                B.B.


        • Edith…
          All guns vibrate to some degree. We can “adjust” certain things to work around it. At least to some degree.

          twotalon


        • Edith,

          I agree that airguns are “toys” that are an engineering marvel.

          It is also totally awesome that Tom has such an interactive blog. It feels like I’m back on the front lines of research participating here.

          Thank you both for all of the fun!
          Herb


          • Herb,

            I’ve looked at firearm chat forums, and most are filled with questions from people who are just out for the biggest bang they can get out of the cheapest guns.

            Airgunners, on the other hand, tend to be introspective, deep thinkers, intelligent, filled with intense curiosity, and lovers of mechanical devices and how they work.

            In my book, airgunners represent the cream that floats to the top of the shooting crowd.

            Edith


            • Edith

              It may be craven and self-serving, but I agree with you. Some folks must put up a front of toughness, which translates to purchases of guns which no one in their right mind would enjoy shooting over any length of time. Luckily I stumbled across the PA blog before I was consumed with desire for useless velocity.

              I love the thought that I am part of an elite group as an airgunner. But it reminds me of a saying, “I would never stoop so low to join a country club that would stoop so low to have me as a member.” Humility is better than pride.



            • Edith,
              You know, most people that I know are of the opinion that air-guns are not “real” in the sense that as an experience, they are not worth the time, or somehow not valid. I’ve probably shot more rounds through “real” guns that most will in a lifetime, and yet with my standards I find that air-guns are every bit as interesting and valid as any other type of gun. My reply is that to me shooting is all about the execution. Doesn’t matter what kind of gun it is, so long as it’s of reasonable quality, the principles are the same. It’s all about execution.

              You see, as a former competitive marksman, I’ve always appreciated the importance of dry-firing. To me, my FWB provided the perfect balance between dry-firing and shooting a live round. A buddy of mine, Dave Kimes, recently told me that during the process of winning a World Championship and setting a World record in 300 meter 3 position, that for each shot that he took, he imagined that he was shooting an air-rifle. From his perspective (an Olympic and World champion), he was a better shooter BECAUSE of air-guns. I totally relate to that.
              Victor



      • I would think that going to PCP like the AA would head more in line with what we are looking for. Vibration will still be a factor, but I would think that it would be primarily the buzz produced as the pellet runs through the barrel. There will still be tank “ping” , hammer strike energy, and some stock vibration, maybe some barrel whip (caused by sudden extreme pressure like pressurizing a garden hose) but i think the complex vibration pattern changes should be much less severe and have much less effect than we have now.

        When it comes to shooting smooth bore, gyroscopic forces on the pellet disappear and you are running on aerodynamics only. This could hurt or help with some pellets, as flaws in pellet shape or balance could cause unpredictable results between rotating and non-rotating pellets….
        Let’s say that a pellet has a pretty good shape for aerodynamic stabilization. But what about balance? May get worse with spin.

        Just guesses there. Possible example of what might go wrong.

        At best, I would think that we would come up with at least two sets of data. Maybe we could determine which pellet is least critical of spin and / or velocity?

        Too much work for me to even think about.

        twotalon


      • Really interesting series of articles, B.B. Herb, great point about repeating these experiments with a smoothbore.

        B.B., since we all know that you have unlimited time and resources, I wonder if Mr. Quackenbush could provide a smoothbore barrel along with those two others of varying twist rates, as a “control.”

        -Jan


    • twotalon

      You said it brother. I’ll give you an Amen and a Hallelujah. I’m certain Matt61 is also a witness.

      That is appeal you can’t deny. Take Crystal Ackley for instance. She is an absolute beauty by anyone’s standards. No plastic, hype or pomp and circumstance. Just a natural ‘girl next door’. If that weren’t enough, she’s a damned good shot, and genuinely seemed to be enjoying herself. Her enthusiasm fueled my own. She would be a 10 in my book without being a shooting enthusiast. The concept that she would enjoy a shooting session makes her even more attractive, if that were possible.

      BB shot with her on multiple occasions. Perhaps he can add to the mosaic. Keep it clean BB, Edith is watching.

      I agree with you about the awarding of the Big Shot prize. If I submitted a photo of myself, and another photo of Mrs. Slinging Lead, there is no question who would win the prize…. unless I was wearing my mexican luchadore outfit with the cape. I might have a slight edge in that case.


      • SL,

        Perhaps you can give all of us a peek and make your avatar the image of you wearing your Mexican luchador outfit with cape. Actually, I thought guys just wore clothing…I didn’t know guys had “outfits” :-)

        Edith


        • Edith

          Of course us guys have ‘outfits.’ How else do you think we attract suitable females? With our table manners? I think not. ;-)

          Don’t try to tell me that BB’s outlaw costume from Frontier Village isn’t pulled out of the closet every now and then.


      • You be right about Crystal. I could never remember what kind of guns she was shooting. I didn’t care.

        One episode bummed me out as being pretty lame. They showed PCP filling with a pump and a tank. The LAME award goes to Paul. He filled with a tank. Poor Crystal got the pump. I know she did not really pump up that gun, but the whole idea of who did what was LAME LAME LAME.

        twotalon


        • twotalon

          With all due respect, I think you are missing the point. Watching Crystal operate the pump was poetry in motion. I’m not trying to get pervey, or diminish her as a legitimate journalist. But, all things considered, I was happy to see her operate the pump, while the somewhat less attractive Paul operated the tank filling procedure. I also think she is more than capable of pumping up that rifle.

          While I was disappointed with her departure from the show, I wish her the best of success. She is a class act.


      • SL,

        Crystal Ackley is the real deal! She got hired for her presence on camera (looks). Who knew she would turn out to be such a good shot?

        From the little time I spent with her filming a few episodes on American Airgunner, I can tell you that she is a genuinely nice young lady, as well.

        B.B.


        • Apparently American Airgunner couldn’t last without you and Crystal.

          From: admin@thesportsmanchannel.com [mailto:admin@thesportsmanchannel.com]
          Sent: Saturday, November 12, 2011 9:26 PM
          To: sportsman
          Cc: Michelle Scheuermann
          Subject: From sportsman: [TSC ADMIN] Contact Us Received

          Thank you for your interest in Sportsman Channel. Unfortunately, American Airgunner is not returning this year and we are uncertain when, or if, it will return in 2012. We are in communication with them and hope they continue with Sportsman Channel

          Happy Holidays
          The Staff at Sportsman Channel


          • American Airgunner had a very good run in my opinion and I hate to see it go. It covered a lot of very interesting subjects and provided sound basic techniques and instruction for new and future airgun owners. But it’s got to be hard to come up with 30 minutes of programming every week. Even with as much detail as BB puts into his blog articles, any given article wouldn’t fill more than 10 minutes of a TV show. Most of them can be read through in five minutes if you don’t read the 100 comments that follow. And I don’t know how you’d go about televising our comments. :-) Even “Top Shot” would flop if they just shot and weren’t doing all that other bazaar stuff. Hey, it might be cool to do a show called “Meglio Diabolo” and duplicate every “Top Shot” episode only use airguns and produce big explosions like they do. They could have an episode where the winner has the most accurate 5 shot group with the largest helix – ending with an explosion of course.


          • Kevin,

            I sent your Sportsman Channel email response to Pyramyd Air, and I was told this:

            “American Airgunner Season 4 will air Q3 and Q4 of 2012. Only the network that will host the show is undecided.”

            So, the show is definitely coming back. If I hear anything else, I’ll post a comment in that day’s current blog.

            Edith


      • I witness and I endorse! And I’ll go you one better. I would say that the torch lit by the fabulously gorgeous Russian women snipers has been ably carried by the new generation as seen here.

        http://www.youtube.com/watch?v=zAtnS6fXcgU&feature=related

        Disarming is the word that comes to mind. Maybe Duskwight can tell us if these are really soldiers. If so, who in the world would want to fight them? I would follow them to a garbage dump and beyond….

        Matt61


  3. Very careful work. You might consider some graphs of groupsize v velocity; I think this would make the trendlines obvious.

    A test whose results would interest me is the use of a pellseat. Some portion of pellets have gravely damaged skirts, some look – to farsighted eyes – quite perfect. A pellseat can make the flattened ones superficially identical to the perfect at the point of loading. I wonder whether that operation has any serious effect on accuracy. The intuitive guess is of course that there is a curve of enhanced accuracy, high with the initially damaged pellets, sloping to minimal with the perfect ones.



    • Yes, yes. A graph would be good. I’m finding with all the variables that I am like that Far Side cartoon with two physicists standing before a blackboard full of equations. One’s head has deflated like a flat tire, and the other one is saying, “Ha, ha. Webster’s blown his cerebral cortex.”

      Simon, thanks for the info on the two points of zero.

      Matt61


  4. twotalon,

    “That extra energy has to go somewhere. Usually ends up in vibration.” Wish I’d thought of that. Such an excellent point. You are defiantly on to something and I am waiting to see you idea plays out–THANKS.

    Bruce


    • Maybe a “best” rifle to test with does not exist.
      Let’s say a AA S400 (single shot loading) with it’s adjustable power range….with a barrel 6″ thick to minimize vibration effects? Too heavy for hunting. At least for me.

      Then we would have to send it to AlanL to “adjust” the twist rate for another series of tests.

      twotalon


    • On top of that….
      Power plant vibration and barrel vibration caused as the pellet rubs through it are two different animals if you do not tie them together. Then there are stock vibrations that are caused by both.
      Where are we catching the power curve? In a fairly stable spot, or is it ragged ? A ragged power curve is going to change vibration patterns from shot to shot.
      Then all this stuff interracts .
      Stock screw tightness has an effect too. How are we coupling all these forces together?
      A rifle that vibrates horribly can still shoot good. One that shoots smooth (as far as the shooter can tell) can shoot horribly. We can’t see all of the motion that is going on.

      R9#1 (.177) has shown me that sorting FTT into .1 gr batches caused some interesting things….the velocity can change by about 10 fps just by going up or down by .1 gr. Touchy power curve. I am not a good enough shot to see any difference in accuracy though. No point in sorting them other than to toss out any bad ones. A different rifle may produce considerably different results.

      twotalon


    • Let’s throw in another one…
      I did a short test last summer.
      I picked a few kinds of pellets and pushed them through the barrels of the R7 and R9, then I shot the same kinds of pellets into a trash can full of water. Next, I set the pellets up side by side to see what kind of skirt damage I had. Pushed pellets and fired pellets from the R7 looked alike. Pushed pellets and fired pellets from the R9 were noticeably different…..some by just a bit and some by a lot. There was clearly skirt deformation with the R9 with the fired pellets. What happens when the skirt deforms? It has to change the aerodynamics at least a little. Then what about any non-symmetrical deformation? That can’t help.

      twotalon




  5. BB,

    I need to put all your results on an EXCEL spreadsheet and put a chart together to examine all the data. I can’t remember what each pellet did from test to test. My initial conclusion before doing this is that velocity affects each pellet differently. It appears each pellet has a ‘sweet spot” not only for the rifle but for the velocity the rifle propels it at. Because of two variables – rifle and velocity, pellets will have to always be tested in the rifle to be used until the best combination is arrived at – the data may vary too much because of the two variables involved to allow a rule to be developed. Again, this is my initial conclusion.

    A super test with a tremendous amount of effort on your part. At the very least, you’ve continued to build back your muscle tone!

    Fred PRoNJ


  6. How accuracy changes as velocity changes in airguns has always been a deep, mysterious black hole to me. I’ve been very interested in this series since I had hopes for some light to be shed on this black hole. It would be interesting to see a summary of the data in an easily digested form like graphs.

    The decrease of velocity in this series seems to generally confirm that heavier pellets do better at higher velocity and vice versa. The beeman devastator pellets seem to constantly surprise me with their performance since at every turn they have been contrary. Since there isn’t a clear linear progression of pellet weight, accuracy and velocity we logically should start questioning the usual suspects like exact pellet weight/weighing pellets, skirt deformation, vibration, cant, parallax, ideal hold, lube vs. unlubed pellets, etc.

    I know that the unique vibrations/harmonics in each gun has an affect on poi and accuracy for every given pellet. I had a gun with an old vortex brake that could be adjusted similarly to a hots or boss system. While testing with one pellet you could adjust the brake and although groups would tighten a little the poi would change dramatically. I’ve also changed scopes on guns and their favorite pellet changes. Vibrations? Harmonics? Off shooting day? Inconclusive for me. It’s also been my experience that a spring guns favorite pellet changes after I’ve had the gun tuned even if the velocity change was minimal.

    Sorry for the rambling since I don’t have any conclusions. Seems this black hole in airgunning just gets deeper.

    B.B.,

    What scope did you use on your Whiscombe during this test? Was it ever removed or moved during this test?

    kevin


    • Kevin,

      I’m just as befuddled by this whole thing as you. All that I know how to do is experiment with pellets and guns to see what works best for me. On the other hand, I have to admit that I enjoy trying different guns and learning what level of performance I can extract from them. An odd thing is that I tend to gravitate towards those guns that cause me the most heartache. The eternal optimist in me keeps telling me that there’s some secret there that needs (can) to be uncovered. Yes, I’m willing to shoot many tins worth of pellets in the process. Aside from just the notion of discovery, I also do appreciate the opportunity to work on my fundamentals. Difficult guns make the need for proper fundamentals more apparent.

      Victor


    • Kevin,

      The scope is a Simmons, I believe. The rifle is away from me right now, but I will look next time. The scope wasn’t touched once during the entire test.

      Like you I had hoped for some sort of linear relationship to emerge. but what I see looks different than that. At least it does right now. I’ll have to analyze the data before I know for sure.

      If I can take the rifle to some point where it was either accurate or inaccurate and then alter that with the HOTS, then velocity may not be as important as we thought. It may be trumped by harmonics. I’m not saying that it is at this point, just that it could be.

      B.B.




        • Victor

          Yes! with one of those mounts that looks through the scope. Steve, Harry, and Ted over on the Yellow have posted some fascinating footage with this setup. It really shows the subtleties of a pellet in flight. Sometimes its hard to believe we can get such small groups with these crazy things.


        • RE: Camera

          Ok. I think we have just changed BB’s wish list for Xmas. Ted is using a Casio EX-FC150 which retailed for $300 or less. I think that model is now outdated. Everything electronic these days seems to be on a 6 month cycle. $50 adapter to mount camera to scope.

          For range shooting I still think mounting to a spotting scope above rifle would be the way to go. Through the scope is sexy, but the scope bounces as the shot is taken, even with a PCP. I’m sure that the end of the barrel is worse.

          Herb


        • I had explained to a friend how difficult it was to get good groups from my Ruger Air Magnum, and he suggested one of these rifle-scope mounted cameras so that I could better analyze the shot behavior. I told him that this rifle would destroy such a camera, as it had already destroyed two scopes, shattering the lens on one of them. With that, I have to agree with Herb that a spotting scope mounted camera might be better. Back in my target shooting days, I found that you can actually see the bullet just before it hit the target (contrast of black bull versus sun reflection off of the bullet), if you placed the spotting scope just right. I can’t help but thinking that being able to do such a visual analysis would add significant insight as to how well a certain pellet matches up with a particular rifle at a specific velocity.


          • I hadn’t thought about the vibration killing the camera. My thought was that if mounted above the rifle that you could mount the camera (optics system) looking down along the line that the pellet impacts the target. At 10 yards the line is nearly flat, but shooting out to 50 yards there is quite a bit of curvature to the pseudo-parabolic flight of the pellet.

            The other thought was that a spotting scope would have more magnification, and with a larger lens it would gather more light. The more frames per second, the more light you need.

            Regards,
            Herb


          • I just found out about a device that the British used to teach marksmanship with Lee-Enfields. Judging from the picture it was a device with mirrors whereby an instructor standing at right angles to the shooter and right in front of the breech, could coach you on the sight picture. Highly distracting I would think.

            Matt61


  7. B.B.,
    I think twotalon and Kevin are on to something with efficiency and harmonics. Even though you can choke back velocity and power with the Whiscombe, the power plant bore and stroke stays the same. Maybe those big pistons don’t really like breathing through a little restrictor. An auto analogy would be the British made McLaren road car. It will idle around all day, but would rather be on the Circuit de la Sarthe at full chat. I think you may need to use another rifle and compare results. Maybe burying a barrel and receiver in concrete to eliminate another variable?
    -HM


  8. I’m going to start out my comment with a plea…..PLEASE explore at the very least,the effects of adjusting the HOTS with the best pellet/velocity AND the worst pellet/velocity combination.The results of your hard work so far would only be enhanced that much more with this result included.My Whiscombe doesn’t allow this unique ability because I can’t adjust velocity via the transfer port.
    I DO feel bad asking,but from your wording it seems you WANT this asked.To not do it would be like a trip to the moon without taking a soil sample IMHO.I mean,we know that the HOTS works by allowing you to adjust vibration to get the pellet out of the barrel at the “optimum” time in the vibration pattern.The conclusion seems logical that simply changing the speed of said pellet also changes that critical alignment of where in the vibation behavior the pellet makes its exit.My $.02


    • Frank

      Great suggestion. Word is, BB was running out of blog topics. ;-)

      HOTS would make a great blog, especially among the filthy masses such as myself that don’t own a Whiscombe, and want to know more.


      • Maybe if you cut down on the so-called “necessities” ie…food,clothing,utilities,shelter…..you could scoop one up! LOL,folks that don’t know me might assume I’m some sort of airgun SNOB SlingingLead.
        Not much could be further than the truth.I wish we all lived in the same area! I would keep ALL my airguns in a rec-center,and give you guys each a key.My greatest frustration is being unable to share our hobby (in person).That is why this blog is so great,for sharing our experiences worldwide and you can’t beat the price either!!


        • Frank

          I am in complete agreement. Sometimes my wealth of airguns embarrasses me. I can’t imagine how you feel. ;-)

          We are not so far apart, adjoining States in fact…No good excuse for us not to get together sometime. Unless you dislike house guests that won’t leave.

          Just out of curiousity, what do you think might happen to a person with a couple dozen rifles in the trunk should they be pulled over by Alabama’s finest?


          • Assuming they were yours (and NOT mine)……I would hope nothing would result.In my own experience the real misunderstandings occur when airguns are in use,and viewed by non or anti gun folks.You can quickly be percieved as the boogie man or some lunatic.Responding Law Enforcement personell MUST
            aproach the situation as very dangerous…..for their own safety! Once it is realized that it was a case of mistaken identity…….there may be residual bad feelings or embarrasement in play.That can result in an ill concieved criminal charge of “menacing”,which unfortunately can be difficult to disprove.This actually happened to me involving a cowboy costume and cap gun being removed from the trunk of a car on Halloween! A judges wife just happened to drive past as the cap gun fell from the holster to the ground!
            I can assure you a judges wife is NEVER wrong………


    • Frank,

      Yes, I am planning on doing the HOTS test. If I leave the rifle set up the way it is right now, I already have a baseline to start from.

      B.B.


  9. The Browning BOSS (ballistic optimizing shooting system?) functions like the HOTS. It works. You really can dial it sequentially, measure groups, and make your bullet and charge group as well as possible. And that’s what really made it worthwhile. Pre-Boss, you could select a bullet that performed well and do endless fussing with charge weight and primer and overall length in the hopes you could emit the bullet at a stable node and get a reliable group. Like as not, your best group came at some inconvenient (read, feeble) velocity. With the BOSS, you could pre-define the load for the bullet and velocity you wanted, then make it come out at the stablest possible position in the barrel-whip sequence. The effect was reproducible; you could shoot other loads with their own BOSS setting, then return to the setting for your regular load, and have it print the usual group. We found that with some qualifications – cleaning the barrel, good handloading techniques, quality ingredients, .etc – that we could make that .30-06 produce 0.75 MOA groups with every bullet weight we tried. I have no doubt that with the HOTS you could avoid the endless, if pleasant, sequence necessary to find what pellet your gun shoots well; you could just choose the pellet whose in-flight or terminal behavior gratified, and make it shoot well. A vibration-tuning system of one sort or another has been in use for many decades on target .22s; I have a Winchester 52 bull gun made in the 40s or 50s with the tuner at the tip of the fore-end. Some of the modern target .22s make use of easily-slid fat rubber o-rings at or near the muzzle.

    An interesting treatment of barrel harmonics, and the way loading can time the arrival of different parts of the barrel-whip cycle at the muzzle is here:

    http://optimalchargeweight.embarqspace.com/


  10. Seems to me the data are already on paper. Can’t you just line up the targets by pellet type in decreasing velocity order and take a photograph.Wouldn’t we be able to see the groups changing size as velocity changes?


    • Chuck,

      I’m afraid it wouldn’t look like much if I did it that way. Some of the targets are so close in size that I think it will take the measurements to tell any difference.

      B.B.


      • BB,
        I had already considered that, and in my mind, if the results are that close then any measurements taken will be unreliable because of the naturally induced variables we all see in our day to day shooting. So, if all the targets are that close, then you have only discovered that velocity does not affect accuracy very much, if at all. Yet, I’d say the experiment is still a success because knowing velocity doesn’t affect accuracy very much is, in itself, useful to know. However, as a side experiment, have we proven that POI changed with the different velocities you used?


  11. BB,
    I think there might be some significant trends if you graph the group sizes vs. velocity for each pellet as suggested above. Also, some simple tables with the data would be useful, as it is really hard to sort through the individual tests right now because each pellet has a different velocity (depending on its mass) — really more like group sizes with various kinetic energies.

    Harmonics may be a good thing to explore, but there are also other factors, such as how velocity affects spin rate and how that is suited to or unsuitable for each pellet at each velocity. The Eu Jins, I suspect, being long and heavy are not terribly well stabilized by drag alone and need adequate spin just like bullets; at least that is one thing I think may be going on in the last test, especially, where they are erratic. I.e., are they more accurate at higher velocities because of aerodynamics, or is it a result of their stabilization or lack thereof.


  12. I remember experimental barrels in the early 90s that were made with steel in the center, with the rifled bore of course, then other alloys on the outside, they had no “ring” just a dull “tunk”. No resonant frequency!

    Today was crazy, rode like 40 miles on my damn cargo bike because one silver buying place was closed so I got pissed off and rode to the other one in the town that’s closer to me. I got some targets for my Ruger .22 pellets experiment, which I *will* get done this weekend, plus …. a Daisy 880 with a scope!

    So I’ll have the 880 to play with, it may be more accurate in my hands than my Delta Gamo with open sights.


    • OK I should post some clarifications here. First, I got paid for some stuff with two Silver Eagles, and not being in the silver-investment game, wanted to sell ‘em. I also had some sterling off of some candle holders.

      I’m feeling really good about the 800s, people with cool accents like this dude shoot one:

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

      And it goes through TWO vegetable cans with 10 pumps!

      I am honestly, not very dangerous with my Gamo unless it’s a shot I’d actually do with a decent pistol.


  13. RE: Pellet rifle vibration

    Look at the two links in this post on the Yellow. Video for HW90 springer and HW100 PCP. (Blow youtube vids to full screen.)

    http://www.network54.com/Forum/79537/thread/1276198490/Interesting+videos+—

    For the HW90 you can actually see the rifle vibrate before the pellet exits the barrel. It isn’t clear how the rifle is being held, but almost certainly not like it would typically be shot. It still gives you some idea of the power in the harmonics for a springer.

    Herb


    • Nice videos,…thanks for sharing the link.

      In regards to the HW90, I am surprised at how much the action moves within the stock. Those videos were very iluminating for me to say the least!!!


    • Very fine films. I was interested to see that in one springer shot it appeared that the action actually separated, or tried to, from the stock. That’s violence.

      Herb, could you repost your link to the films showing the helical trajectories? Somehow I missed it and now can’t find it.

      pete




          • pete,
            I want to thank you, too. You’ve shown what probably is the best way to show BB’s results. And I agree that vibration needs to be removed from the test to make sure it’s not the culprit in influencing the accuracy.


          • Pete,

            Started a new thread on yellow about Harry’s videos.

            http://www.network54.com/Forum/79537/thread/1323657742/Precession+of+pellets

            Harry posted another video of the Gamo pellets.

            http://smg.photobucket.com/albums/v392/Kyogle/?action=view&current=VideopellettestA-1.mp4

            The video above shows even more clearly that the pellets are precessing in a counter-clockwise direction. In his reply to the yellow post Harry also confirmed that the barrel has a right-hand twist.

            Regards,
            Herb


            • I put the following on the Yellow. I don’t have time to work out the physics of the fully free top subject to aerodynamic as well as gravitational forces, but my instinct from years of physics points me in this direction.

              –pete

              =========================

              I think what we’re looking at is a completely free “top” spinning with an aerodynamic force tending to restore the top to an orientation parallel to the instantaneous velocity, and a gravitational force tending to force the nose of the pellet down, tipping the tail up. Most physics reference books only treat a top with one point fixed spinning on a table top, so finding a treatment of the whole problem is difficult, and very tough mathematically. Nevertheless, plunging right in without math:

              Early in the trajectory the angular velocity is very high, and the gyroscopic forces can lift the nose and keep the pellet aligned. As it slows down that becomes less possible and the nose of the pellet begins to nutate. Finally, it becomes rather like a top when it slows down and the top begins to tilt and finally fall. There is probably a critical combination of linear velocity (which produces the aerodynamic forces) and rotational velocity at which wobble becomes significant and the pellet begins to spiral around the trajectory. I think I expected to see a spiral in the direction of the pellet rotation, but was fooled by the fact that the tail of the pellet (skirt) is so big. That makes us think the CM (center of mass) is further back than it is.

              –pz


              • Pete,

                Mostly agree with you. The second order differential equations can’t be solved unless you make some simplifying assumptions. In order to create any numerical models we’d have to have all sorts of data which are beyond our poor means to collect. But spool rockets, badminton birdies, bullets, mortar shells, and round balls provide different insights to the problem. Each different type of projectile would have its own unique set of simplifying assumptions.

                The direction of the precession is well understood for projectiles. It has to do with the relative positions of the center of gravity and the center of pressure. For bullets the CoP is in front of the CoG, for drag stabilized projectiles it is the opposite.

                The problem in reading articles and books is that rarely does the source specify if the projectile is (1) spinning or not spinning, and (2) spin stabilized or drag stabilized. Each of the four cases would have different flight characteristics.

                I disagree that the apex is particularly significant. Shoot a pellet absolutely horizontally and its flight will still reach a critical point downrange where the flight becomes unstable.

                I think that for pellets this would happen even if you shot the pellet straight down towards the center of the earth. So gravity isn’t a dominate factor. I think that this is another part of the difference between bullets and pellets.

                I think the early stability of the pellet is due to form drag stabilization. In this part of the flight the pellet is akin to a spool rocket. Spinning helps average out the mass imbalances and small aerodynamic irregularities, but by and large it is form drag that dominates at this point. (Remember that smooth bores do reasonably well at 10 yards.)

                Later in the pellet’s flight form drag loses dominance since the velocity is slowing.

                If the precession is slow enough, then the CoG and CoP follow the same spiral. At that point all “accuracy” in shooting is lost. This is essentially the point that the top falls over.

                I think the model to imagine is initially the pellet rolling/sliding along the inside of a tube initially which is just slightly larger than the diameter of the pellet. So the pellet is flying in a tight helix which is just slightly larger than the physical diameter of the pellet. At this stage of the flight the slight precession will be in the same direction as the spin.

                The key here is to realize that it is impossible that the actual center of mass is absolutely on the aerodynamic center line of the pellet. So just as the pellet clears the barrel, the “lateral throw” would have the pellet precessing in the same direction as the spin. Since the spin and precession would be “tightly coupled” at this point, the precession is occurring at too great a rate for the pellet to follow its nose. So the CoP and the CoG are traveling helices of different diameter but along the same average center-line.

                There is some slight yaw angle though, and the gyroscopic force is slowing the clockwise (cw) precession. Finally the cw precession is slowed to zero, and the pellet starts to precess in the counter clockwise direction. Now the precession is slow enough that the pellet can “follow” the precession angle and the pellet starts to fly in a spiral instead of a helix. So at this point the CoP and GoG are both following the same spiral. Now instead of the spin rate/precession rate coupling there is a yaw angle/precession rate coupling.

                So the pellet’s flight is a problem due to the interaction of form drag and gyroscopic yaw. Gravity is not the key contributor to the flight problem.

                Regards,
                Herb


              • Pete,

                I’d add that what we are looking for is a semi-empirical equation which has a few terms which we could adjust based on simple experiments or observations.

                I’m absolutely convinced that the drag coefficient of a pellet isn’t a constant from 300 fps to 900 fps. The empirical relationship for BC however is good enough so that measuring the BC of a particular gun with a particular pellet works well enough to be useful.

                For a pellet though there is also the precession rate/yaw angle coupling, particularly at “long” distances. So there are some interactions that would be near impossible (require much more sophisticated, $$, equipment than we have) to measure.

                So can we do some other calculations from first principles to get a reasonably close approximation to this interaction? Then we’d be able to see how some pellets performed in our particular rifle and predict relative performance of various other pellets.

                Given a good enough model we’d be able to predict the form factor for a pellet from first principles.

                Regards,
                Herb


                • Herb,

                  By and large I concur. I don’t think that the apex has a damn thing to do with it; pellets do not follow a particularly markedly curved trajectory — we just draw it that way to see what we think is going on, and sometimes we’re wrong. Consider a particularly tall athlete shooting 10 m. Let’s make him 2 meters, about 6′ 8″ tall shooting at a target that is the standard 1.4 m above the floor. Then there is no apex to the trajectory; he’s always shooting from above the target…

                  What is a spool rocket? The term doesn’t mean anything to me. Do you mean a wire-guided missile like a TOW?

                  Of course the drag coefficient isn’t a constant over that range of velocities, even if they are all subsonic.

                  –pz



                    • Yes. Basically two discs connected by spindle. The dual discs have a very high form drag. But to have stable flight there is a fairly limited range for diameter/distance.

                      Think it is close to wadcutter. For wadcutter the conic tail is mostly hidden behind head so the drag of tail is just due to a small ring of cone.

                      Regards,
                      Herb


  14. Can we say if there’s anything that looks like a sweet spot in the data?

    Hilarious about the garbage dump the other day. Edith, the guy must have had something to lure you out to a garbage dump and take you on a wild motorcycle ride. Surely, they didn’t happen on the same evening. As for men wearing outfits (like Slinging Lead’s), according to one novel, the Joker’s first words to Batman were, “Nice outfit.”

    I didn’t know that B.B. wanted a motorcycle. Staying away from them is probably a good idea. The military in Hawaii are always crashing them and suffering horrific injuries. But, B.B., take heart, it could be worse. My grandmother banned by grandfather from computers. Actually, I think it was more of self-denial because, as he said clapping a hand to my grandmother, “I would neglect this little lady here.” He had a brilliant technical mind and was quite capable of losing himself in a computer. But he was much less tractable about his ban from golf which was definitely imposed by my grandmother. She had it in her head that something would happen to him out on the golf course, and he would be far away from help. He would complain about this ban, sometimes in the presence of family, hoping to embarrass her I suppose, but she never relented. But I would not worry about a motorcycle ban for eternity. In the Great Beyond, you and Edith can ride around as fast as you like with no fear.

    Matt61


    • I like motorcycles too but I am aware of just too many bad accidents involving them so I stay away. Of course when I was young that wasn’t a problem as I was immortal then. But, as to being banned……..not now, not ever, never!

      Mike


  15. B.B.,

    I have several tins of different types of pellets that apparently have small diameters (smaller than, say, CP’s). Can you think of any air-guns that have bores that are particularly smaller in diameter?

    Thanks,
    Victor


    • Don’t feel like the Lone Ranger. I have a bunch of pellets that are too small for anything I have too.
      Some are so small that I doubt if ANYONE has made a barrel that they would fit…even with the sloppy tolerances that some manufacturers use. Then there are the barrels that are bored so large that the largest pellets don’t fit either.

      twotalon


    • Victor,

      Most Weihrauchs have constricted breeches, and Lothar Walther barrels are minimum. Also the FB 124 has a choked breech.

      B.B.


    • I have a tin of Chinese pellets that I bought when I ordered a B-3 from Cummins. Although they are marked .177, they literally fall through the barrel of all of my guns when the muzzle is pointed down.

      /Dave


      • And on the OTHER end of the scale… I once tried some “Valor” pellets from I-don’t-remember-where. They were so oversize I had about a 30% failure rate in a Crosman 357 and a Marksman 2004. The pellet would just stay in the breech while the gun went “pffffffft”.


  16. I received my .22 Discovery, pump, scope, case and a spare tank last week from a couple of guys, on the yellow! A tank adapter hose and valve is on the way from another. Only got to play with it a little, but I’m pleasantly surprised with how easy out is to pump up, shoot, how small and light it is, and it’s accuracy with JSB Exact Heavy’s. It’s also pretty loud, but I think I can find a muzzle brake/weight to help with that. I don’t see what the fuss with the trigger on a Discovery is, since this one seems to be pretty good! (There’s always room for improvement, but this one seems pretty nice already, compared with my 2240, 1322 and 397! :-) ) Can’t wait to get it to the range for some longer range shooting!

    So, I guess I’m on the dark side here… Actually, it’s pretty bright! Nice job on this one, BB! :-)

    /Dave


    • Dave,

      perhaps some work was done on the Disco trigger? If you want a two stage trigger with light weight and insignificant creep, I highly recommend the TKO22 trigger from Mike TKO. Go to TKO22.com for muzzle brake and trigger. I am very satisfied with both kits.

      Fred PRoNJ


      • Thanks, Fred! I’ll try him out. The disco is second hand, so I don’t know what may have been done to it, just that it works fine! I do need a little more backyard friendliness though. My neighbors are pretty tolerant of my noise, but I don’t want to push my luck… :-)

        /Dave


  17. Hi, folks. I couldn’t resist making a plot of the velocities v. group sizes so far. I’ve never tried Google Docs before; can you see this?:

    https://docs.google.com/open?id=0BzTeeknoHtv_MzNkY2E3ZWMtOTA2MS00ZDQyLTkyNjMtY2RkODFhYjE0OTMw

    Apologies for my caveman excel practices; much like my shooting style.

    I find it interesting that three of the pellets’ minimum group sizes are clustered around similar velocities. And that in B.B.’s Whizzer, these minima are not so much in the 850-950 fps region that I often hear folks advocate.

    -Jan




      • Hi, fellas. It does look a bit better in excel than the way Google renders it in a browser. If you have Excel on your computer, you might want to choose “download original” and fire it up directly in excel rather than letting Google display it.

        If I were better with Excel (or perhaps if Excel were better at plotting), I woulda’ put a vertical “mach 1″ reference line, and maybe some horizontal per-pellet and average minimum velocity lines.

        -Jan


        • GenghisJan,
          I didn’t think to study the groups to see if they were vertical or horizontal (we know they were shot with a level). Looks like I still have to go back and have a peek.



  18. Pete,
    Is the one you’re looking for?

    Herb Says:
    December 10, 2011 at 11:13 am
    RE: Pellet rifle vibration

    Look at the two links in this post on the Yellow. Video for HW90 springer and HW100 PCP. (Blow youtube vids to full screen.)

    http://www.network54.com/Forum/79537/thread/1276198490/Interesting+videos+—

    For the HW90 you can actually see the rifle vibrate before the pellet exits the barrel. It isn’t clear how the rifle is being held, but almost certainly not like it would typically be shot. It still gives you some idea of the power in the harmonics for a springer.

    Herb

    Reply



    • Well, it’s not so silent, for one thing.

      As a general rule it isn’t good to dry-fire a spring gun because very little air pressure is building up in front of the piston to slow it down, and at the end of its stroke it hits home rather hard. This shock puts greater stress on a variety of parts and can damage them.

      Granted, the damage from a single dry-fire is usually insignificant. But the cumulative effect of several can start to screw things up. So if you accidentally dry-fire on the rare occasion, it’s probably nothing to worry about. But don’t make a habit out of it!

      Side note – about 7 years ago Gamo used to say in their literature that you COULD dry-fire their guns, but they’ve stopped making that statement in later years.


  19. i know that the tx 200 is not a vibrate free gun but it is a good air gun and it dont vidrate like some guns do so is that the velocity of the pellet or not


    • Well, I shoot my TX at around 930 f.p.s., so the velocity never gets too high. I never tested it at 1,000 f.p.s., though it’s certainly capable of shooting that fast with some pellets.

      B.B.


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