Ultimate Reloader and Bryan Litz discuss long range performance of 22LR.
22 LR Mach Trimming
- Thread starter Longshot231
- Start date
Litz says that at just above the speed of sound, the drag on a .22LR bullet increases enough to cause it to slow down faster than than a round that is below the speed of sound. The result of this is that ES of sample of shots fired downrange will be less beginning at about 30 yards or so than closer to the muzzle.
I was not aware of this phenomenon -- mach trimming. It offers an explanation other than flatter trajectories for the desirability of MVs averaging around the speed of sound and just above.
Litz also confirms that, while group convergence doesn't occur with centerfire, sometimes it does occur with .22LR. In other words, sometimes (not very often) groups shot with the exact same ammo in the test tunnel can produce groups that are MOA-wise smaller at 100 meters than at 50. He says it helps to understand what happens by envisaging a corkscrew trajectory. He said modelling has helped to illustrate what happens.
In this regard, the difference between jacketed centerfire bullets and soft lead .22LR bullets may help explain why it happens only with the latter, not with the former. Unlike jacketed bullets, soft lead bullets (and airgun pellets) are much more difficult to produce with nearly perfect centers of gravity. Variations in center of gravity of bullets going downrange result in them having more unpredictable trajectories, perhaps even causing the corkscrewing that Litz thinks of when describing convergence.
I was not aware of this phenomenon -- mach trimming. It offers an explanation other than flatter trajectories for the desirability of MVs averaging around the speed of sound and just above.
Litz also confirms that, while group convergence doesn't occur with centerfire, sometimes it does occur with .22LR. In other words, sometimes (not very often) groups shot with the exact same ammo in the test tunnel can produce groups that are MOA-wise smaller at 100 meters than at 50. He says it helps to understand what happens by envisaging a corkscrew trajectory. He said modelling has helped to illustrate what happens.
In this regard, the difference between jacketed centerfire bullets and soft lead .22LR bullets may help explain why it happens only with the latter, not with the former. Unlike jacketed bullets, soft lead bullets (and airgun pellets) are much more difficult to produce with nearly perfect centers of gravity. Variations in center of gravity of bullets going downrange result in them having more unpredictable trajectories, perhaps even causing the corkscrewing that Litz thinks of when describing convergence.
Here's another video on mach trimming. I haven't had time to watch it yet but post it anyway.
https://thescienceofaccuracy.com/podcast/113-mach-trimming-of-22-rimfire-velocities/
https://thescienceofaccuracy.com/podcast/113-mach-trimming-of-22-rimfire-velocities/
Known since long ago (at least to some of us). Designers of pistol cartridges shooting into transonic know for that from roughly WWII times, but I dunno if they called it by some special name.
Didn’t have the new names (Mach trimming) but has been explained and documented by many for decades. Same for convergence, people got chewed up (myself included) for noting this publicly, just because it wasn’t “acknowledged by a name”.
Wait till they rediscover some barrels cause slugs to fly in a helix to the target!
I’m waiting for the center fire guys to come in and turn this into a positive compensation /tuner disaster thread because they keep trying to use rimfire to explain center fire.
Even though he said this was not seen during jacketed testing
I’m hoping it doesn’t but this is the hide so you never know
Even though he said this was not seen during jacketed testing
I’m hoping it doesn’t but this is the hide so you never know
I had a video of the cork screwing he talks about. I was shooting cast bullets out of my 308 win at distance and it was leaving a very visable smoke trail. You could see in slow motion the bullet spinning but at the same time the bullet flew in a cork screw looking way. It had 2 types of spin going on in the same way.
I wish I could find it. Because it could show a lot of the things we talk about but don't get to be able to see. I am confident this may be the flyers we all get that is happening.
I wish I could find it. Because it could show a lot of the things we talk about but don't get to be able to see. I am confident this may be the flyers we all get that is happening.
I think what they were getting at in the videos was that the groups were not smaller at distance. They were smaller than expected.
The group sizes were larger at distance than at the distanced they rifle was zeroed, when it came to actual dimensions measured in inches. When measured in MOA (the angular measurement) they were smaller.
With Longshot's point that the smaller groups are smaller MOA-wise only, it's important to note that when convergence does occur, it's a random consequence, one that's relatively unusual, and unexpected. In other words, they are an unpredictable outcome that can't be produced on demand.
Convergence is occasionally seen in testing tunnels where the exact same rounds' group sizes can be compared at both 50 meters and 100. When this unexpected outcome occurs, the 100 meter group is smaller MOA-wise than it was at 50 meters. Any results obtained comparing groups at the two distances shot with different rounds can't be considered valid, even when they come from the same lot, because the comparison must be apples to apples.
The cause of random convergence is associated with variation in the center of gravity of the soft lead .22LR bullets. Furthermore, not only can bullet Cg vary from lot -to-lot, even bullet-to-bullet, the center of gravity is also affected by the unique Cg changes contributed by each individual bore's role in bullet obturation.
Center of gravity variation explains why some lots or groups of rounds exhibit more or less dispersion as distance increases. It also helps explain why some bores are better at long distance than others, even when they both shoot well at closer distances.
Now do cg variances vs twist rate. Rimfire is a rabbit hole.
Try shooting it in a 16-18" barrel. SK long range match is definitely supersonic for me, and it's very noticeable with a suppressor. I was doing some lot testing the other day and came up with this from a B14r.
SK makes high velocity match. My Bergara didn't like it, but my old Marlin shoots moa with it
SK High Velocity Match | Rimfire ammunition | .22LR
The new SK High Velocity Match exits the muzzle at 1,263 feet per second (385 m/s). High Velocity Match strikes on-target with both speed and precision.
sk-ammunition.com
MOA- wise of course, wasn't that clear from my post?
That's what I'm thinkin' as well!
Well, I thought about how "trimming" could be applicable to my shooting.
It isn't going to useful except as a topic of conversation over coffee on range mornings.
The effect is going to be minimal on my results for multiple reasons.
I shoot outdoors under less than optimal conditions.
Rimfire cartridges available for purchase are rarely at a level of quality where "trimming"
would be noticeable due to the effects of cartridge problems on trajectories.
At extended range, my skills aren't good enough to allow the effect to be observed.
It isn't going to useful except as a topic of conversation over coffee on range mornings.
The effect is going to be minimal on my results for multiple reasons.
I shoot outdoors under less than optimal conditions.
Rimfire cartridges available for purchase are rarely at a level of quality where "trimming"
would be noticeable due to the effects of cartridge problems on trajectories.
At extended range, my skills aren't good enough to allow the effect to be observed.
My Eley Match is quite fast. Avg 1103 at 10C. There are a few that would in the Mach trimmer zone. I’m curious what will change when I go from 20” to 24” barrel.
That's just a few feet faster than what SK long range averages in my 22" Vudoo. Typically about 1106.Try shooting it in a 16-18" barrel. SK long range match is definitely supersonic for me, and it's very noticeable with a suppressor. I was doing some lot testing the other day and came up with this from a B14r.
View attachment 8379530
SK makes high velocity match. My Bergara didn't like it, but my old Marlin shoots moa with it
SK High Velocity Match | Rimfire ammunition | .22LR
The new SK High Velocity Match exits the muzzle at 1,263 feet per second (385 m/s). High Velocity Match strikes on-target with both speed and precision.sk-ammunition.com
Various Lots of SK long Range in my 20" Vudoo will average anywhere from 1113 to 1120 at 10 C. That will increase up to as high as 1135 with temperature increase. So the ammo is running right at Mach 1. I can't say that I have noticed anything like Mach trimming as when the occasional round that has a muzzle velocity 20-30 fps above the average produces an obvious flyer outside of the group.
I believe that is more due to different conditions bullet is facing just after it excites the muzzle than going little bit more transsonic trajectory than the others (ie. more yaw induced)
IMO to call the phenomena convergence is misleading. The corkscrew path taken to the target by an out of balance bullet winds around the trajectory of an otherwise equal but balanced bullet. There is no convergence of those lines, only apparent convergence at the target and that is a random event for our purposes.
Perfect loop flying paths exist only if the total angle of attack vs trajectory = 0 all the time. This is achievable only in ideal world and point mass ballistic models. In reality certain level of the "corkscrew" is always present (perhaps not for uniformly rotating or nonrotating spherical shot). Example for 0.223 cal (vertical and horizontal positions of M855 bullet recorded at Mach 1.4-1.5) can be seen posted in thread:
Transonic Cone Theory of Bullet Motion
Well there you go, I don’t have the litz books handy. I guess all that is left is to convert radians per second to rpm’s but I’m not convinced that’s the right formula and at a minimum doesn’t tell the whole story. Also that white paper is for artillery and requires the installation of a...
www.snipershide.com
For bullets to "converge" repeatedly, at certain target range, would be quite difficult experimentally to set. Larger lounch yaw levels and appropriate spin rates are 2 parameters to look for, but that's not enough
That prolly why Aquila Super Extra 40 LRN did much better with it being 1147fps range out of my LH B14r. May have to revisit this again when I get a chance.
So... warm up the ammo to literally have it shoot 'hot' and fast.
With the mach thing, it seems like you can make ammo that has a low ES, but that is expensive- or maybe get ammo that is often transonic and let the mach limiter bring down your ES. Or I guess even with a low ES ammo, the mach limiter may help?
I was listening to it while I worked, but the bullet is facing 40Gs of deceleration from aerodynamic drag? Was that for CF or RF? That's pretty interesting..
I'm still amazed at the crap left by RF rounds in the barrel... That seems to me to be a major variable, but I guess not.
The other comment I heard was about the lube on the bullet. My meat paws are always smearing the lub putting the round into the magazine. That can't be good...
With the mach thing, it seems like you can make ammo that has a low ES, but that is expensive- or maybe get ammo that is often transonic and let the mach limiter bring down your ES. Or I guess even with a low ES ammo, the mach limiter may help?
I was listening to it while I worked, but the bullet is facing 40Gs of deceleration from aerodynamic drag? Was that for CF or RF? That's pretty interesting..
I'm still amazed at the crap left by RF rounds in the barrel... That seems to me to be a major variable, but I guess not.
The other comment I heard was about the lube on the bullet. My meat paws are always smearing the lub putting the round into the magazine. That can't be good...
They posted a slow-motion clip a few years ago of the .22LR slug exiting the muzzle and traveling about a foot. You can see that at a couple of inches after exit, the residue that was pushed out but is stuck to the slug, peels off or is spun off by centrifugal force or air resistance. It would be interesting to compare video of consistently accurate rounds against those that fail to group, and also of different barrel lengths, to see what effect if any this residue has on accuracy.
I would like to see some better cleaner powders developed so the bullet don't pick up as much junk that laying in the barrel. Perhaps this may mitigate some of the accuracy issues. It's worth a thought. I also think it's time for better design of bullets since it's going on in the CF division which were unheard of 15-20 years ago.
Remnants of gun powder and lead debris make difference yes. As of 22LR bullet design, it is already close to optimum and only little heavier and longer projectiles should have some advantage. Good material and tolerances control is the best way to go. I guess it is quite difficult to introduce boat tail designed lead alloy bullet for 22LR.
Most likely I would embrace some enhancements in 22LR ammo, but isn't the allure of shooting 22LR for extreme accuracy working around the ammo itself?
No history, but off the top my head I will say that I may not fare well shooting against someone with handloaded solids. Then again, do I even consider handloaded solids even 22LR ammunition.
It's still fair for all involved.
I seem to like pissing money away, the most expensive 22LR ammo I know of borders .60 per rd, yet I have capped myself at around .42. I doubt that I will pay .80 per rd just to be even more eccentric.
Shooters, especially those coming from centerfire, have always desired improved .22LR ammunition. Too often the nature of related discussions convey the impression that .22LR development has remained mired in the past and its performance largely unchanged and unimproved. This isn't the case. A key problem is that with an round that was designed well over a century ago there's only so much that can be done while keeping costs within affordable limits.
From the early use of .22LR, improvements have been made, from crimping the bullets in the casing (it wasn't done until .22 repeaters came into use) to the use of improved powders and priming compounds over the course of the ammo's nearly 140 year history. At no time in it's history has priming technology been better than it now is. At no time, has the loading and manufacture of .22LR ammo been better. When new improvements in components or manufacturing become available, they will be put to use as they have in the past.
Nevertheless, shooters eager for significant improvement have sought it in many ways, including faster twist barrels, handloading custom made bullets with pre-primed cases, and the widespread use of tuners for shooting at all distances the humble .22LR round can reach.
The manufacture of .22LR match ammo is such that the same nearly perfect lots of ammo can't be produced in efficient ways. Ammo performance always varies by lot. The best way to get better ammo remains as it always has -- testing different lots to find what shoots best for the purpose at hand. The use of faster twist barrels or tuners doesn't change that.
From the early use of .22LR, improvements have been made, from crimping the bullets in the casing (it wasn't done until .22 repeaters came into use) to the use of improved powders and priming compounds over the course of the ammo's nearly 140 year history. At no time in it's history has priming technology been better than it now is. At no time, has the loading and manufacture of .22LR ammo been better. When new improvements in components or manufacturing become available, they will be put to use as they have in the past.
Nevertheless, shooters eager for significant improvement have sought it in many ways, including faster twist barrels, handloading custom made bullets with pre-primed cases, and the widespread use of tuners for shooting at all distances the humble .22LR round can reach.
The manufacture of .22LR match ammo is such that the same nearly perfect lots of ammo can't be produced in efficient ways. Ammo performance always varies by lot. The best way to get better ammo remains as it always has -- testing different lots to find what shoots best for the purpose at hand. The use of faster twist barrels or tuners doesn't change that.
Well, if one counts all the problems with unjacketed lead projectiles, it's amazing that 22LR can achieve submoa groups at 100 yards. For comparison, there have been efforts with top grade bullets of centerfire pistol rounds, like 9 mm parabellum, and as regards accuracy, AFAIK all quite dissapointing. With carefully handloaded FMJ projectiles in weight class 100-150 gr and from custom made precision barrels, PCC guys could not shrink the groups down to 1 MOA. Experimental muzzle velocities are 1000-1400 fps (just like 22LR), projectiles look like this:
Althought match grade ammo is expensive, 0.6$ per 22LR rd I consider really too much.
GECO or Sellier&Bellot 9 mm 115 Gr centerfire target ammo costs about 0.4$ per rd where I live.
S&B 22LR plinking ammo is about 0.1$ per round.
My 22lr addiction rapidly bifuctured into 40HV for AR/handgun blasting, and 40g subs for 200+/LR bolt gun shooting. As the latest/greatest 22lr ammo for long range is approaching fifty cents a round, that gives me pause.
I think great gains have been made, and while the mach spliting is interesting, the other part of the conversation discussed better ballistic calculators for 22lr- and I think that would benefit as much as anything. I've never gotten a CF calc to work with 22lr and the simple observation of come-ups at 200lr from cold morning to warm afternoons definately points to some gremlin out there.
While the whole highly accurate long range 22 is something I enjoy, what I think would really benefit shooters, and line up with the advantages of 22lr, is the inclusion of different targets- and moving targets, like Hoser has in some of his matches. That is where 22lr as quarter scale 308 could be really interesting.
I think great gains have been made, and while the mach spliting is interesting, the other part of the conversation discussed better ballistic calculators for 22lr- and I think that would benefit as much as anything. I've never gotten a CF calc to work with 22lr and the simple observation of come-ups at 200lr from cold morning to warm afternoons definately points to some gremlin out there.
While the whole highly accurate long range 22 is something I enjoy, what I think would really benefit shooters, and line up with the advantages of 22lr, is the inclusion of different targets- and moving targets, like Hoser has in some of his matches. That is where 22lr as quarter scale 308 could be really interesting.
OT a bit but am offering options.
When I ran out of the case of Lapua Polar Biathlon, that I had bought through testing at the Mesa facility a decade ago, I refused paying the stupid prices we pay nowadays to buy more PB.
Then two years ago bought a case of Wolf MT at $8.something which is almost as good as the Lapua.
I'm drawing the line at $10 a box of 50 from now on.
I did find some other deals that were substantially less last year.
But that brings me to my next point and it is that pcp airguns using slugs/lead bullets are creeping ever closer to 22rf.
Some of the better pcp's are pretty expensive though and very nice as well.
Once a person has bought a decent compressor the air is almost free.
Some slugs aren't very expensive.
Other slugs can be a little pricey but offer higher BC's than 22rf bullets. My 25 cal Altaros 60gr slugs have a .245G1BC.
Slugs can be swaged at home and the lead wire is only $160 for a 25 pound spool. In my 22 cal slug gun that makes 4400 slugs. My Thomas HPX slug rifle will outshoot my Anschutz 22rf at 50Y and is even with the 22rf at 100Y. BC is .142 for these slugs.
A HUGE benefit with airguns is they can be tuned down to 3-5 fps SD!
Also the velocity can often be adjusted to compensate for different temperatures.
The downside is precision for most airguns isn't quite to 22rf at 100Y yet overall. Some do exist though that are pretty amazing. Here's one recent 100Y target shot with a 22 cal Thomas slug gun. No its not mine.
Just sayin.
When I ran out of the case of Lapua Polar Biathlon, that I had bought through testing at the Mesa facility a decade ago, I refused paying the stupid prices we pay nowadays to buy more PB.
Then two years ago bought a case of Wolf MT at $8.something which is almost as good as the Lapua.
I'm drawing the line at $10 a box of 50 from now on.
I did find some other deals that were substantially less last year.
But that brings me to my next point and it is that pcp airguns using slugs/lead bullets are creeping ever closer to 22rf.
Some of the better pcp's are pretty expensive though and very nice as well.
Once a person has bought a decent compressor the air is almost free.
Some slugs aren't very expensive.
Other slugs can be a little pricey but offer higher BC's than 22rf bullets. My 25 cal Altaros 60gr slugs have a .245G1BC.
Slugs can be swaged at home and the lead wire is only $160 for a 25 pound spool. In my 22 cal slug gun that makes 4400 slugs. My Thomas HPX slug rifle will outshoot my Anschutz 22rf at 50Y and is even with the 22rf at 100Y. BC is .142 for these slugs.
A HUGE benefit with airguns is they can be tuned down to 3-5 fps SD!
Also the velocity can often be adjusted to compensate for different temperatures.
The downside is precision for most airguns isn't quite to 22rf at 100Y yet overall. Some do exist though that are pretty amazing. Here's one recent 100Y target shot with a 22 cal Thomas slug gun. No its not mine.
Just sayin.
Good design of a subsonic (<0.9Mach) projectile includes (quasi)elliptical nose cone, a cylindrical body of appropriate lenght and BT of appropriate parameters. Such projectile are stabile in a long flight downrange, maintain low drag and provide better accuracy than SP BT projectiles. Seems that people from Altaros know what they are doing!
Altaros is the Co I use in my Vulcan 3 which puts out 99 fpe using the 60gr. I won a UFT match using these 60gr/25cal in February/ 5 points higher than 2nd place. Great slugs! I don't have to hold out as far as the 22rf shooters and about a 5th as much as those using pellets.
The 100Y hold for these slugs in a 10mph full value is .5mil but .9mil for 22rf.
Been times at 300Y, while windy, when I could stay on the steel with these slugs and saw less success with the rimfire when shooting both within minutes of each other. My 22rf rifle is no slouch, has shown very good precision using tested ammo, and has helped me win my share of matches.
Sorry, OT, so I'll stop posting here concerning airguns.
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