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taylorce1

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Here is an interesting video on Mach Trimming, on Ultimate Reloader with Bryan Litz. It's pretty chewy, and Litz knows far more in his little toe nail than I'll ever fully understand about ballistics. You can visibly tell how excited Litz is in his .22 lr research. It is definitely worth a watch, and thanks to rimfire shooters in competition like NRL driving rimfire sales right now changes are coming.
 
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I am a GIANT fan of Brian Litz's work, and have a number of his research articles saved. This is interesting indeed. I love how he's revisiting converging groups. He studied that some years ago and theorized how hypothetically it could occur, but concluded that he couldn't make a model that showed convergence and he still wasnt a big believer in the phenomenon. I studied it a lot as I have a rifle that shoots converging groups. For the life of me, 100 yard groups are .8-1 moa, while 300 yard groups are .5-.6 moa.

This Mach trimming discussion is really interesting. And opens the question of convergence back up, though Brian appears to feel that it mostly applies to subsonic or barely supersonic rounds. The man is a genius, and he's done a lot more for our sport than most realize. Think back to the early days of these forums when most people balked at the idea of an out the box rifle that shoots sub-moa. These days, no one questions a person who claims a production bolt gun shots sub-moa groups. Certainly manufacturers (both rifle and ammo) have played a large role in that. But I think Brian Litz's work has contributed as well. Probably a lot more than we realize.
 
LOVED IT! Thanks Taylor. :)

Some of the stuff Bryan mentioned I stumbled upon myself just through sheer volume of shooting and "gee, isn't this odd?" study. LOL. His mach-trimming concept seems to explain with what I've observed with better ammo just emerging from the muzzle at or slightly above supersonic; the initial "hit the mach wall" occurring during the same time the bullet is seeking it's attitude within the first yards of muzzle-exit. I'm not sure he brought it up as an example of a specific distance; but I've found that 200 to 225 yds is sort of "demarcation line" where the better ammo keeps it together and inferior stuff really starts to lose it.

I'm not positive, but I think the RN4 bullet model is in fact what most of the better manufacturers use. I don't know it for a fact--but I seriously doubt ANY other cartridge in any caliber is made with the same level of precision as 22lr is.

I've wasted a lot of time and money trying to find the "magic supersonic bullet" that really does deliver on true long range 22 lr shooting. I think a key aspect to the existing 22lr performance is what Bryan mentioned--in a way the all-lead bullet is being "fire formed" by the the throat and bore. The existing approaches to what I call "long term supersonic"--say, over 1250 fps, seem to rely on a jacket of some sort or a monolithic high SD design. I've never had consistent results with either of these approaches that will predictably beat the best existing all-lead at or slightly above supersonic ammo.

Bryan seems to be saying at the very least he's going to develop better predicative modeling for 22lr trajectory solutions. It's tempting to think he's also going to get tempted to go down the rabbit hole of developing a true high performance long range 22lr bullet. Hard for me to see how that's possible with the existing constraints of the 22lr as it is now on the market--but if anyone is up to it--I bet he's one of them.:)

I wonder how team Berger will feel if he joins team Lapua?:D:D:D

At the end of the day, unless you are willing to design a new chamber--all you're talking about is 2 to 5 grains of propellant most of the time.
 
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Thanks for posting. He is really in a class by himself on the subjects he deals with.

There are lots of approaches that are still left to be explored with the .22rf IMHO and I am glad he is doing it. It's a catch 22 (pun intended) to go down the rabbit hole of performance of .22rf slugs, air rifle slugs, etc. around Mach 1 and slower. In most rifle shooting, the thing is to avoid transonic and just throw up the hands when you get there. I expect, we will learn some things no-one has even thought of yet if he keeps at it.
 
I've watched the video several times now, trying to glean a kernel or two more. I'm really interested in what he'll discover.
 
Over complication takes all the fun out of reloading and shooting ...
It doesn't have to be rocket science and I'm not a rocket engineer ...
I like to Keep It Simple ...
Gary
 
Is it a round about way to say trans-sonic chaos be damned, and let the sonic wall regulate the speed?

Interesting he mentioned .22lr bullet has some resemblance to pellet. It is a heeled bullet, meaning it is front heavy. CE is still in front of CG, but distance between them (the moment arm) is shortened. When the airspeed (bullet speed in-flight) is low enough, the negative feedback system for stabilizing the bullet may not have enough "loop gain" to work effectively. That's my explanation to the quick accuracy degradation beyond certain distance. Given the caliber was meant for much shorter range, the off-label application of long range shooting is expected to be weird.

The twist rate is quite low. Faster twist may help extend the range, I think.

-TL



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Is it a round about way to say trans-sonic chaos be damned, and let the sonic wall regulate the speed?
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Funny--that's not at all how I took what he said.;) The way I took his meaning was that the present centerfire modeling does not work reliably for 22lr--possibly because the portion of supersonic flight has a much shorter but more profound effect on the trajectory of the 22lr bullet. He also mentioned that he's never found conclusive evidence of convergence in supersonic centerfire ammo--but he has seen evidence of it possibly happening in 22lr. My speculation is that Bryan probably is not going to suddenly become a dedicated rimfire addict--but maybe sees the additional study as a means of furthering his understanding of all ballistics (?). Still--I'm overjoyed he's taking the dive.:)
 
2 messages I picked up. One is the failure of the traditional bullet models for .22lr, although the success they have enjoyed for high supersonic center fired bullets.

I wouldn't be too surprised about that. Those models are mostly optimized for supersonic flight. We routinely discard the trans-sonic and subsonic part of the flight. .22lr is either totally subsonic or short supersonic+trans sonic+subsonic. Also, I agree with him that, the stability of .22lr at low speed is questionable.

Message 2 is the idea of mach trimming. A string of rounds fired, average speed at speed of sound, some above and some below. Supersonic drag is higher. So after some distance their speeds become similar. In order for it to work, one must venture into trans sonic zone.

-TL

Sent from my SM-N960U using Tapatalk
 
I've been rolling that Mach Trimming concept around in my head since I saw the video a couple days ago.
Still hurts the few remaining brain cells as I try to figure out how to use the information.

Mark and Sam video is interesting, as well.
Not much different than my own testing and (some) match use of Blazer 40 gr RN (1,235 fps) and ... I forget ... one of the SK loads that is supersonic.
Short range groups may not be as good as some other things, but they're more consistent down range and, of course, let me reach farther with the elevation adjustment that I have in my scopes (especially with the "slow" 16 inch barrels).

Got myself a new rifle last month, the Hammerli Force B1. Because, why not.
Not shooting great so far. Absolutely fine for the average person, just not "match grade".
And also remodeled the boy's match rifle at the same time. So as I build new dope for both rifles before our next big match (in April - too soon!), I might give a little more attention to some HV loads.
 
I guess there isn't a direct application just yet. It is just an idea he has in his mind. A theory if you will. Basically it is to have a load with average mv right at speed of sound, and sound barrier will tighten the SD. It is an interesting thought but not sure about its practicality.

For us meer mortals, there isn't much really. It is rather difficult to load our own .22lr.

-TL

Sent from my SM-N960U using Tapatalk
 
Also, I agree with him that, the stability of .22lr at low speed is questionable.
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Actually, the inherent stability of the predominant 22lr bullet design at slower speeds is outstanding and pretty much stays that way as velocity decays--that's a totally different thing from the external effects of when it is fired and the environment it's flying through.;):)

I like Mark and Sam's stuff too and watch it all the time--mostly cause I'm jealous he has such a nice place to shoot long and he records it all. Does his wife have a sister? I could use a full-time spotter; especially if she can cook and do the dishes.:D:D

(just kidding)
 
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tangolima said:
Mark and Sam after work from Australia shoots a lot of long range stuff. His take on supersonic vs subsonic .22lr ammos. I pretty much share his view point
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I wasn't a lot of ammunition shot in that video, but I think it tracks with what Bryan Litz said in the video I posted. Where he found on average subsonic bullets gave less horizontal dispersion, and supersonic gave less vertical.

SK match was 10.45" H by 3.66" W
CCI SV was 11.08" H by 5.58" W
FED HV was 6.01" H by 6.77" W
CCI Vel was 6.22 H by 4.13" W

Like I said the amount of ammunition Mark and Sam shot isnt a definitive test either way. But their experience I bet tracks with what Bryan is finding out.

It's all good stuff to ponder over and discuss here for sure.
 
@FrankenMauser, what are your thoughts on that Hammerli? I've been looking at it as a cheaper way to get into a .17 HM2 without going Volquartsen. I could just go with a Savage for around $400, but I've been eyeballing that Volquartsen Summit for awhile.
 
Just out of curiousity--I went to CCI's website and looked at the performance of the velociter ammo used in the M&S vid. The supersonic "pushback" (my word, not his) that Bryan mentions in his vid is such that the 300 to 400 fps supersonic "advantage" is gone before the bullet reaches 100 yds; the slower supers much sooner than that. In my mind, that alone sorta "nullifies" the notion that a supersonic 22lr is inherently more accurate at long range. Lapua's newest "super long range" ammo is another that leaves the muzzle hovering around the transonic transition--it isn't even 1,200 fps. I betcha that is what catches Litz's attention.:)
 
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The general belief is that trans sonic is chaotic zone one should avoid at all cost. Mark & Sam's video is to show trans sonic is not always that big of a deal. Litz's idea is to purposely enter trans sonic zone.

Even though HV ammo loses its speed advantage within short distance, say 75yd, there is advantage nonetheless. Flight time is still shorter with HV ammo.

-TL

Sent from my SM-N960U using Tapatalk
 
The general belief is that trans sonic is chaotic zone one should avoid at all cost.

The only way to do that is to use a subsonic bullet all the way through the firing process.

Mark & Sam's video is to show trans sonic is not always that big of a deal. Litz's idea is to purposely enter trans sonic zone.

I don't think it's a question of transonic tranistion is an "either/or" proposition--it's when it occurs and how much it effects the predicatable trajectory of the bullet.

Even though HV ammo loses its speed advantage within short distance, say 75yd, there is advantage nonetheless. Flight time is still shorter with HV ammo.

What Is that advantage? Greater accuracy through all ranges? Greater stability through all ranges? Who has accurately measured and recorded all that and then developed an effective model for predicting the bullet's trajectory to long distance? I don't think anyone has--and hence why I take it to be Litz's principal interest.
 
The advantage is shorter flight time, and hence less exposure to air mass disturbances, cross wind, up/down draft etc.

Longer flight time also leads to higher vertical speed of the bullet caused by gravity. It doesn't help vertical stringing.

-TL

Sent from my SM-N960U using Tapatalk
 
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