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hypervelocity 22 lr research

Discussion in 'General Gun Discussions' started by tech30528, Mar 18, 2012.

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  1. tech30528

    tech30528 Member

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    Hello all, been catching your threads online in research for some time and decided to join.

    Ok, so first some background. I'm a numbers guy. I love math. I'm a 42 year old L1 ASE Master auto tech and own an auto repair shop. I absolutely love the 22 lr platform and am mostly a target shooter. I have several 10 22s that are well built for specific purposes and a couple of 22 pistols as well.

    I've tested over 20 different kinds of ammo with different rifles for varying distances. My personal favorite over thousands of rounds of testing is the CCI AR Tactical. For overall accuracy and dependability I find that these are the best. Granted all three of my test rifles are 10 22s, but they range from nearly stock to full custom.

    My recent adventure is stretching what some consider the usable range of the 22lr. To give you an idea, we are shooting pingpong balls off golf tees at 350 feet with a 10 22 with a 17 inch Majestic barrel using 1200 fps ARTactical ammo. Granted, I weigh my ammo and separate it by .1 grain increments. I have a rim gauge but I've found rim variation to be nearly insignificant.

    In order to stretch the range of these rounds I've gone to testing hypervelocity rounds. What I've found is that they just don't group well. But I know why. These hypervelocity rounds are smaller. The standard 1/16 twist barrel is over spinning them. Using the modified Greenhill Equation, I find that these shorter rounds require a slower twist rate.

    Now, Green Mountain makes a 1/18 twist "Stinger barrel", but that barrel is heavy, and I like my rifles light. So after contacting several different barrel makers, I found one willing to make me a slower twist aluminum barrel. For the blanks he had available I couldn't, get a 1/18. What he could get was a 1/20, which is what is used for 22 shorts. Look at the grain weight of a 22 short vs a hypervelocity 22lr. Pretty close, huh?

    So, I've done a lot of testing so far and still have some to do. Just wanted to know if anybody else might want to get in on this discussion. I'll tell you this: I just outfitted that custom rifle. With a 20MOA drop scope mount because I ran out of adjustment on my 24x scope at 150 yards and I'm still grouping pretty well with what I consider to be subpar ammo.
     
  2. firesky101

    firesky101 Member

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    There is only so far you can go with velocity. At a certain point, heavy slow bullets have less drop due to the momentum overcoming the drag better. For accuracy generally heavy is the way to go. I am looking to get the 1:9 volquartsen barrel for stabilizing the Aguila 60gr SSS.
     
  3. rcmodel

    rcmodel Member in memoriam

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    Yep!

    You should have ask.

    Lots of .22 shooters here could have saved you the money & time testing them again.

    rc
     
  4. VA27

    VA27 Member

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    I've done the small bore/long range thing, only I went the other direction. Instead of hypervelocity, I use CB caps. I genned up some reduced paper silhouette targets. At one hundred yards they appear to be one thousand yards away. Computing drop is fun, and you better be able to read the wind. I've also shot the CB's on a handgun metallic silhouette range (rams at 200 meters!) and have gotten a few others to try it. It's great fun, but not for the easily discouraged!
     
  5. JohnBT

    JohnBT Member

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    The problem with hypervelocity rounds at longer distances is that they don't stay above the speed of sound all the way to the target. As the speed drops from above the speed of sound to below the speed of sound the turbulence knocks them off course. Think of it as a reverse sonic boom if you will. Ever see the film of the X-1 breaking the sound barrier? Shake, rattle and roll.

    There's a reason rimfire target shooters use standard velocity ammo even at shorter distances. It's subsonic.

    John

    edited to add: Speaking of 1 in 19 twist, Gary Mitchell's famous record-setting Suhl .22, Old Blue, was already a record-setting rifle when he bought it from K.C. Young. Mr. Young owns a local range I belong to, so I guess I missed my chance. Although I didn't know it at the time, it's a 1 in 19" twist.
     
    Last edited: Mar 19, 2012
  6. tech30528

    tech30528 Member

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    Ah yes. The transonic bump. I'm well aware of that. Thing is, a lot of high velocity rounds deal with that, it's just a matter of where. For instance, the AR Tacticals (1200 FPS) I like so much are just barely supersonic. They break just a few meters out of the barrel. The transition is somewhat misunderstood as it is not really the sound wave "catching" bullet so much as it is the forward shift of the center of gravity that occurs during the transition. Truncated rounds handle this better, hence the 1 1/4 inch groups I'm seeing at 100 yards with these out of the 1:16 barrel. What I'd be interested in seeing is a truncated 30 grain.

    I don't see the cost of this 1:20 barrel being a loss. It was less than $300, less than my standard ammo order. I shoot a LOT. I have 4 different ranges at my house. Plus it's the only aluminum fluted and threaded 1:20 twist barrel I know of. Thing is much of what we are told about rimfire is old information, and there is a lot of new stuff coming out. For instance, when the PMR 30 hit the market, it had cool factor just because it holds 30 rounds (as did it's predecessor, the Grendel 30), but since the 22 WMR has long been a rifle only round it didn't live up to it's potential in the pistols. Enter the Hornady V Shock WMR pistol round, loaded with a faster powder specifically for the benefit of shorter barrels. So don't accept everything you've heard.

    These smaller faster rounds can be stabilized, it's just that nobody's really done it yet (we'll get in to that later, you might be surprised what these things can do with a slower twist rate). I'm not saying these rounds will rival the WMR, they can't. The case pressures would have to be way too high. But they can come awfully close, and do it much cheaper. This is hobby stuff. If we are going out hunting I'm sure we all have some bigger caliber stuff to do that with. But I'm having a pretty good time on the cheap playing with this, as I imagine some of you are too.
     
  7. tech30528

    tech30528 Member

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    I'll get in to that. I've seen huge inconsistency in batches (no surprise there for any of the rimfire guys), along with some pretty surprising results. For instance, shooting from the same box out of 1:16 and 1:20 barrels side by side.
     
  8. Tinker

    Tinker Member

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    (Disclaiimer: You guys are totally out of my league with this discussion on precision .22 shooting, so forgive a layman's imput...)


    Those cartridges you say are just barely supersonic....could you use additional barrel length (in correct twist) to tame a supersonic round before it leaves the barrel?
     
  9. 230RN
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    230RN Marines raising the left-leaning Pisa tower.

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    ???


    Don't you mean the forward shift of the center of pressure?
     
  10. youngda9

    youngda9 member

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    Are you trying the high-dollar ammo? Like Lapua...that stuff is great.
     
  11. mortablunt

    mortablunt Member

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    Pics, video, and analogies please? It sounds cool and fascinating, but I don't really grasp that physics stuff.
     
  12. tech30528

    tech30528 Member

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    Ok, a few things here. I'll try to keep this stuff straight as I did a lot of these tests some time ago (but all within the last year).

    First, additional barrel length will not stabilize the barely supersonic rounds because of additional control. I chrono tested several different rounds including the Aguila SuperMax with 16.5, 18 and 20 inch barrels and there was no significant speed difference. To be fair my focus was to see what I wanted the barrel length to be on that custom one, so I was focusing more on the fast stuff. However, I have a friend who shoots a CZ with a very long barrel and he claims tighter groups with barely supersonic stuff. I suspect what is happening there is that the bullet is reaching it's max speed in the barrel and after near complete powder burn it is slowing down, leaving the barrel subsonic.
     
  13. Old Dog Man

    Old Dog Man Member

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    22 cal. long range shooting

    I have a Rem. 581 22lr, 1/16 twist and have done a lot of testing with various brands of ammo. It doesn't like any of the hyper stuff, it really shoots good with Rem. round nose gold colored ammo. The cheap stuff, it will shoot Aquila ok and rem. target ok. doesn't like hollow points or truncated bullets. I mostly shoot long range PD with it, but am going to take it Fri. to a 600yrd. range and see what it will do on paper. I have put a second screw in the action in front of trigger guard, glassbedded it, recrowned the barrel, and flooated barrel. Have a 6x24 scope on it, longest PD kill Measured 367yrds. longest hit 450yrds. had to slide rifle fordward in bag to see hit on 450yrd. shot, but 367yrd it looked like a little dog setting in bottom of scope. Have wittness but they said they would not back me up because everyone would call them liars too. Now they all have shot them past 300yrds. Don't think I would like a 20moa base on a 22lr. Had one on 25/06 for really long range it worked good. Al
     

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  14. tech30528

    tech30528 Member

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    Yes, I have shot the high dollar stuff. That was a separate test. All of what I shot was subsonic including Midas, Eley EPS, CCI Greentag, RWS and Wolf. Much to my surprise, accuracy was not in the order of cost. I shot about 100 rounds of each with different rifles but all in sets of 10 at a time. So it was two rifles with ten rounds each type per rifle on 5 different sets and in different orders to help eliminate residual lubrication factors. One rifle had the Majestic 17 inch aluminum barrel, the other a Ruger stainless barrel. The tightest groups overall were with the EPS at 34 cents a round, the second was the Midas at 32 cents a round with very little difference between the two. The shocker was the third best with an average group size difference of just 1/16 of an inch larger than the Midas at 100 yards, the CCI Greentag at 16 cents a round. The others weren't even really close.
     
  15. tech30528

    tech30528 Member

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    No. As the round slips subsonic it essentially has a braking effect. You know when you hit the brakes at high speed in your car and the back end comes up? The car essentially becomes front heavy because of the center of gravity shift, it's kind of like that.
     
  16. JohnBT

    JohnBT Member

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    "I suspect what is happening there is that the bullet is reaching it's max speed in the barrel and after near complete powder burn it is slowing down, leaving the barrel subsonic."

    It's a fact, proven long ago.

    There's an interesting article in the current issue of Precision Shooting on the necessity of shooting anywhere from 20- to 40-round groups to actually establish the true center of the groups. His conclusion was that the really tiny, neat little 5-shot groups we all love are not usually where the larger groups end up on the target. Some the author's groups, with some ammo, actually made two distinct groups within the larger 40-shot group.

    Going from memory, he had an airtight building with a car-sized concrete base to mount the return to battery mount he had made. It weighed something like 75 pounds. After testing ammo on the 35 yard indoor range, he moved outside and retested in calm conditions at longer distances.

    Anyway, I need to take the time to sit down and study on what he took years to document.


    "The transition is somewhat misunderstood "

    By whom? It's well known. I was surprised you didn't even mention it. It's probably the largest factor affecting accuracy when shooting hypervelocity ammo.
     
  17. tech30528

    tech30528 Member

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    That's interesting. I haven't played with Remingtons, I'm still pretty new at this. Where I am finding a sight line that long is tough since we are in the mountains. I think I'd like that kind of shooting.
     
  18. tech30528

    tech30528 Member

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    Well, the way other shooters have explained it to me was akin to a jet wash, and in reading I found that it wasn't so much an external force as internal. I've even had some tell me that the disruption is temporary and the bullet will restabilize. That seems a bit odd as it would be difficult to understand how the bullet would "find" it's original track. In other words, if this transition was solely to blame, it would seem that the longer distance from the transition to the target was the larger the spread would be. I would like to read the study you are referring to. I'm by no means an expert on this stuff, it's just that this particular area interests me a great deal and there is not as much information on it as I would like to see. So I end up doing a lot of reading and then doing a lot of shooting while trying to eliminate any repeatable variables, such as having the accuracy of the Greentags affected by left over lube from the previous rounds tested which are different. The RWS and Wolf stuff is oily as opposed to the waxy feel of the Eley and Midas stuff.

    As luck would have it, it seems this was the right place to go to find people who can offer some insight.
     
  19. JohnBT

    JohnBT Member

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    "the center of gravity shift"

    My (limited) understanding is that the Center of Pressure moves forward toward the Center of Gravity in the trans-sonic zone and the shift throws the bullet off.

    The info at the link states that the Center of Pressure is "a function of the body's shape"

    www.fas.org/man/dod-101/navy/docs/es310/ballstic/Ballstic.htm

    I need to find Frank Terrell's work on this. He had movies iirc.
     
  20. tech30528

    tech30528 Member

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    Nice, thanks for that. I'll have to check it out later. The computer I'm on is a relic and doesn't handle video well. It's just back here in the shop for text and schematics and such.

    If the weather holds out I'm planning on some test sets of the Stingers tonight. Shot a couple of strings of the Aguilas yesterday, solids and HPs and repeated my earlier results. I need to get some more Stingers for testing. I'm out of solids and prefer to keep the few segmented hollow points I have left for other purposes. But I've got a couple hundred of the hollow points left, enough for a consistent look at grouping I think. The 100 yard range I use for this has space for 8 targets shooting prone off of a shooter's bag.
     
  21. 230RN
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    I asked about that already. The CG doesn't change in flight. The center of Pressure (CP) may, though, at different and changing velocities, especially in the transonic zone. This depends on bullet configuration.

    Hey, let's remember that the bullet RPM changes with velocity, too. The lighter, hence faster, bullets will spin faster than heavier, slower bullets out of the same barrel with a given twist. Same is true with the same bullet out of shorter versus standard vs longer barrels.

    The Greenhill formula is only a first approximation, and as far as I recall, velocity, per se, doesn't appear as a term, although the spin will change with that velocity with a given twist, so it's "sort of" taken care of in the formula.

    However, since the faster, lighter, shorter bullets will spin faster, the formula kind of falls apart at the extreme ends of the bullet weight/density spectrum. I point out here also that density of the bullet is a significant factor, and most of the lighter bullets are hollow-pointed, effecively giving them an effective lower density.

    However again, (ha-ha), since these effectively less dense bullets require a faster spin, their higher velocities will make them spin faster anyhow with a given twist.

    The formula must also be factored according to the square root of the density of one projectile divided by the density of another projectile of the same proportions. Thus, an aluminum bullet will require SQRT(density of lead [10.9*] / density of aluminum [2.7]) more twist than a lead bullet that has the same profile and dimensions. Twice as much, in fact. (It also depends on the density of the medium through which the bullet travels, which for air in subsonic velocities, is 1.0.)

    I prefer to call it the Greenhill Rule of Thumb rather than formula. He did a good job of trying to nail down all these variables in one mathematical package, but the result is just a starting point.

    Truly it is said that every rifle is a law unto itself.

    And also, every bullet is likewise a law unto itself.

    The Greenhill Approximation eliminates a lot of preliminary testing, but it ain't like Ohm's Law or anything.

    That's why it's so much fun to try different bullets and powders for centerfire loads, but for rimfires, about all you can do is try different brands, styles, etc in a given rifle and obtain conclusions for that particular rifle as to which ammunition is most accurate at which range.

    Terry, 230RN

    * 10.9 is for "average" jacketed bullets. For pure lead it's 11.34.

    REF;

    Hatcher's Notebook, p 556
     
    Last edited: Mar 20, 2012
  22. tech30528

    tech30528 Member

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    Niiice post. Man, that's some stuff to wrap your head around. I did some reverse figuring after testing match grade (subsonic) rounds with chrono testing and found that the "optimum" numbers based on that calculation did not add up, even when using other numbers to compensate for velocity. One thing I did was to use numbers from some extremely accurate combinations (sniper stuff) and use them to proof the equations. While they were reasonably close, even when applied to the 22lr the numbers were off enough to err on the side of slower twist rather than faster. So while the 1:20 I ended up with is actually a little slower than what the calculations came up with (somewhere around 18 1/2 IIRC) it seemed that using the equations available it was better to under spin than to over spin.
     
  23. youngda9

    youngda9 member

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    What size 5-shot groups @50yds are you shooting with your rifles?
     
  24. tech30528

    tech30528 Member

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    It's been a long time since I've shot that close with a rifle. It varies by ammo and rifle of course, but the AR Tactical (1200 FPS 40 gr) with the 1:16 barrel is about 1 1/4 inches at 100 yards. I've kept some of the other targets and notes from some of the other tests, I'd have to look at those to be more specific. Got this one though from Thanksgiving weekend. Pretty indicative of this rifle and ammo combination. The X in the lower left was from my sister in law's set. She was shooting the target below this one. That was a fun day. 4 of us got to shoot that distance with the 22s before breaking out the Mosin and making a mess of a pumpkin.:D
    target.jpg

    50 yards might be interesting for the fast stuff though since that is before the transonic break to see what it would do.
     
    Last edited: Mar 19, 2012
  25. JohnBT

    JohnBT Member

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    "I asked about that already. The CG doesn't change."

    Hey, I'm lucky I remember anything. It's been 45 years since I left home to attend college - as a physics major :banghead:
     
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