The mysteries of 22lr ballistics--what do you think?

[stagpanther]

22lr is a bit of a cult--used to be more shooters here on this forum that discussed it but that group has seemingly dwindled (partially due to stiff resistance to creating a separate rimfire subforum IMO ). I guess most serious rimfire addicts eventually end up on rimfire central.

So, I'm going to venture out and propose some personal observations that are based on nothing more than personal shooting experience and info gleaned from on-line forums. I don't claim anything is a commandment handed down from Moses.

1. Barrel length--I have 3 different barrel lengths from 16" to 28". Top velocity is attained at 16" +/-; so most commercial accuracy barrels and rifles are sold in 20" and less length. I personally have never had any shorter barrels equal the consistency and accuracy at any distance equal that of my 28" tube. I've read about the physics of this on some forums--including thoughts by professional ballistics experts--and there seems to be two schools of thought; the first being that increased length does nothing but slow the bullet down, and a second thought that the increased travel down the barrel "smooths out" the stability of the projectile prior to muzzle exit. My personal experience coincides with the latter, though I can't say for sure why. I've also read anecdotal evidence on the 22lr forums that participants and winners at 22lr comps are rarely, if ever, observed to have used short barrel rifles.

2. Supersonic vs subsonic ammo--I've experimented quite a bit with this, using both factory ammo and my handloads. I've also used projectiles that have better center of gravity and BCs than traditional 22lr round-nose/hollow-points. There are two camps on this subject as well--those that maintain that supersonics are superior--especially at longer distances--than subsonics, and those that say subsonics are the most accurate. I personally have never been able to match the accuracy/consistency of the best factor match grade ammo with any supersonics, including handloads of high BC bullets. There's a caveat--supersonics are a bit more "environmentally resistant" when it comes to the presence of any kind of wind and also ease of trajectory adjustment when going long. Still, in absolute calm conditions, I've never been able to match accuracy with supersonics with subsonics consistently. I suspect the sole exception to this might be where the distance is far enough that the subsonics simply would be falling out of the sky before the supers.

 

[ballardw]

My experience with "long" barrels in .22LR is only in small bore position shooting. Part of the "accuracy" difference was the longer sight radius as the only sights allowed were "iron".

 

[stagpanther]

Part of the "accuracy" difference was the longer sight radius as the only sights allowed were "iron".

Yes--that is often mentioned as the "perceived" advantage of longer barrels. All of my shooting was done with a top-tier high power scope on all barrel lengths.

 

[Unclenick]

While the bullets do start to slow past 16-19 inches (depending on the load, according to Geoffrey Kolbe), the pressure behind the bullet doesn't just vanish. Slowing just means force on the bullet base from pressure is dropping below the opposing force of friction, but this drop-off is very gradual. The reason is that friction force is partly determined by pressure upsetting the bullet outward against the bore. This portion of the friction thus declines with pressure. Friction due to lube viscosity, will drop with velocity. Friction due to pushing (during accelerating) or dragging (decelerating) against the radial surfaces of the rifling changes with those rates of change in velocity. Bottom line: friction is generally on the downtrend in later barrel travel, so velocity losses are small.

In this study of 22 RF rounds from the Ballistics By The Inch project, you can see the 40-grain bullet loads show no significant change in velocity between 15 and 18 inches, and the Aguila 60-grain sub-sonic doesn't change significantly between 11 and 18 inches. Dropping your eyes to the second table you see the 22" Kimber actually shooting them all a little faster, and the 23" Winchester showing a little loss. But overall, it's not much.

If your 28" barrel is always more accurate and you have iron sights on it, then the sight radius explanation is a good one. If it is scoped, it could just have more optimal bore dimensions and the like. But it could also be that if all the rest is the same, the simple fact you have more barrel mass extending out further is reducing muzzle rise around the recoil moment of inertia, and so the gun, overall, just moves less. Long barrel mass certainly slows muzzle change of position due to muscle twitching or trigger slapping and the rest.

 

[stagpanther]

In this study of 22 RF rounds from the Ballistics By The Inch project, you can see the 40-grain bullet loads show no significant change in velocity between 15 and 18 inches, and the Aguila 60-grain sub-sonic doesn't change significantly between 11 and 18 inches. Dropping your eyes to the second table you see the 22" Kimber actually shooting them all a little faster, and the 23" Winchester showing a little loss. But overall, it's not much.

I read some place (a critic of the "by the inch" test) was that some makes actually taper the bore towards the muzzle and therefore advise in shortening barrels it's better to rechamber instead.

 

[MarkCO]

I'm a member of rimfire forum, but I can't recall the last time I was over there. But it is like anywhere else...it takes some knowledge to pull out the wheat from the chaff.

Barrel length AND Velocity... I've had 10" to 26" RF barrels and in my personal experience, which includes building about 200 precision uppers, the bullet velocity and barrel length do the dance together. Some supersonics absolutely do perform better (accuracy wise) from longer barrels as opposed to shorter barrels. I am going to just ditto Unclenick's first paragraph, because I could not write it better. But combining factors, the supersonics, from 20 and 22 inch barrels had the lowest ES and SD on the chronograph. The subsonics had the lowest ES and SD from 16 inch barrels.

Distance is another factor. Bullet shape dances with velocity and distance in the transonic zone. So, if you are shooting past about 100 yards, it needs to be carefully considered. High BC, properly shaped bullets at supersonic speeds WILL outshoot (accuracy) standard lead subsonics out past 100 yards...but at a substantially higher cost. The "round nose" profile with a ball on the end that is typical of 22RF lead bullets is TERRIBLE in transonic, which is why, when looking at relatively inexpensive target grade ammo, subsonics win in the 100 to 300 yard distances. We set up large sheets of paper and shot our .22RFs at varying distances through a 6" hole in a large piece of steel. Absolutely we found where the dispersion due to transonic occurred, and it matched, within a few yards, after the bullets had gone subsonic. There was no question that the subsonics were beating the supersonics in group size from 110ish to 130ish yards and further out, by a LOT. If you are under 100 yards, it really does not matter as much. BUT, I did find that most of the match chambers have a preference for subsonic velocities as opposed to supersonics. The chrono will help one tell what works best for them. Indoors, under 100 yards, standard chambers...supersonics have some advantages.

I settled to using 16" barrels with match chambers and subsonic ammo as the best combination for me. My Tactical Solution Team receiver and bolt with a Thermofit Kidd barrel is insane, and regularly outshoots bolt guns.

 

[Jim Watson]

Once upon a time, a smallbore shooter who wanted a long sight radius and short barrel time could resort to a front sight base extension or a "bloop tube."

 

[44 AMP]

Other than a brief mention in passing in the OP, I don't see anything related to handloading here. I see discussion on barrel length, velocity and accuracy in rifle barrels.

moved to Art of the Rifle, general...

 

[stagpanther]

But combining factors, the supersonics, from 20 and 22 inch barrels had the lowest ES and SD on the chronograph. The subsonics had the lowest ES and SD from 16 inch barrels.

Very interesting point you bring up. I've stumbled upon some discussions where the "normal laws of physics that apply to centerfire cartridges do not apply to rimfires." If you look at Cutting Edge's load tests for their high BC solids--you'll notice that their best accuracy results often happen along with the presence of fairly high ED/SD (not that they are cause and effect related) My experience with transonic effects have been the same as your's in relation to optimal distances out to 300 yds +/-, with the exception that my longer barrel and subsonics does better at all distances inside of that.

 

[taylorce1]

Are you going to try that new Norma or Lapua ammunition for the ELR rimfire crowd?

 

[stagpanther]

Are you going to try that new Norma or Lapua ammunition for the ELR rimfire crowd?

I've heard about them but haven't seen them available yet. They are two of the best major production 22lr providers IMO--not quite as custom as say RWS, Ely and SK--but generally more affordable than the "top tier" stuff. Once you get up into higher pressure stuff the tolerances of the chamber becomes more important, especially with bentz/match type chambers.

 

[taylorce1]

I'm not there yet with .22 LR. I'm wanting to hit a soda can to cantaloupe sized target with my rimfires. Since these are live targets, I tend not to push the distance much past 100 yards unless I'm shooting a magnum rimfire.

I've tried a lot of the standard velocity stuff in my 18" Bergara BMR. It seems to like the Aquila Super Extra 40 grain SV ammunition the best with Norma Match and CCI SV a close second and third. I do have two bricks of Norma Tac-22 but haven't shot any yet.

 

[tangolima]

A bit of my observations shooting 22lr to train for long range center fire.

High-speed (supersonic) is better than standard-speed (slower supersonic), which is better yet than quiet (subsonic). I think the shorter flight time outweighs the adverse effect of trans-sonic. I now can hit soda can sized target, or even smaller, with around 50% probability out 175yd. Beyond that it all goes down the crapper. Trans-sonic?

Trans-sonic is controversial. Some believe, and they have demonstrated, its effects minimal. I'm not sure in my case. But I'm quite certain high-speed is still much better than subsonic. Plenty good enough training for me already. I constantly need to hold 4moa and more for the wind. I try to read it right the first shot, or to correct for it with a quick follow-up shot. Both failed, I try again after waiting a couple of minutes.

-TL

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[stagpanther]

I've done a lot of testing out to 225 yds with both "subsonics"--what I think they are really doing is stabilizing at the transonic boundary as they leave the muzzle IMO--and supersonics--and in my CZ 457 the subsonics beat the supersonics every time if there is no wind. Typically the subsonic bullets are all-lead with lubrication and the supersonics are a similar projectile shape to the sonic leads but covered with a thin metal jacket. I've also done a lot of handload testing with the newer high BC solids like Cutting Edge's CURX--essentially you're going to need a purpose-made for-the-bullet entirely custom match barrel to get those to work well. You also are going to have to develop a tolerance for blowing case heads off and debris in the face while working up loads.

So, my personal theory is this--I know the folks over at rimfire central will get a good laugh out of this: 22lr was designed from the beginning to have soft lead bullets to impress into a very short "freebore (more like a forcing cone IMO) and easily mold to the grooves and lands on the way out the barrel. Metal jackets or solids simply don't conform as well IMO to the "traditional" 22lr chamber and bore design. Another thing about supersonic bullets, they hit the wall very quickly due to very small capacity cases, typically the cases are increased in length and sometimes thickness in order to handle higher pressures. At some point you're knocking on the door of wildcatting and you might scratch you head wondering is it worth it or should i just move on to something like 22 mag?

 

[tangolima]

Flight time in air shorter the better. Long flight time amplifies effects of any variations. Even without wind long flight time of subsonic will eventually show its shortcomings. Shooting outdoor is hard to have no wind. A little wind pushes the poi big time.

I also found that keeping the rifle level is very important. A little canting makes noticeable miss. Again it has to do with long flight time.

It is good emulator to long range center fire shooting.

Soft lead may not be able to deal with higher speed well. It may strip through the riflings. The copper plating on supersonic bullets makes it strong enough for that.

-TL

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[micromontenegro]

Theortically, it is easier to make shorter barrel more accurate, because of shorter vibrations. Real life results, I have never shot any rimfire approaching the groupping of my Annie 1408 ED Super... 18 inch barrel.

 

[imp]

I want to offer one thought that has been bothering me a bit recently. I think the shorter barreled rifles are just harder to shoot well. I'm certainly no world class shot, but I know when I've made a good shot and when I've made a poor shot, and I seem to make more poor shots with a shorter barreled rifles, even off a rest. Maybe due to more weight forward of the rest balancing the rifle on the rest holding it just a little more steady...

 

[MarkCO]

I want to offer one thought that has been bothering me a bit recently. I think the shorter barreled rifles are just harder to shoot well. I'm certainly no world class shot, but I know when I've made a good shot and when I've made a poor shot, and I seem to make more poor shots with a shorter barreled rifles, even off a rest. Maybe due to more weight forward of the rest balancing the rifle on the rest holding it just a little more steady...

That is fundamentals. Not related to the inherent accuracy of the barrel. But if longer works better for you, then no reason to get a shorter barrel.

 

[Bart B.]

Flight time in air shorter the better. Long flight time amplifies effects of any variations. Even without wind long flight time of subsonic will eventually show its shortcomings. Shooting outdoor is hard to have no wind. A little wind pushes the poi big time.

I also found that keeping the rifle level is very important. A little canting makes noticeable miss. Again it has to do with long flight time.

It is good emulator to long range center fire shooting.

Soft lead may not be able to deal with higher speed well. It may strip through the riflings.

Then why is 22 rimfire match ammo muzzle velocity the slowest?

 

[tangolima]

Then why is 22 rimfire match ammo muzzle velocity the slowest?

Depending on the type of match perhaps? Distance, indoor or outdoor. And of course $ per round of the ammo. Indoor, no wind, consistent MV, subsonic will keep its advantage over supersonic

Supersonic's problem is trans-sonic zone. Some said fatal, and some said no big deal. The kind of shooting I'm doing, I favor supersonic. Not to win matches or to break records, just to knock over tin can beyond 150yd, outdoor with wind. I found supersonic doing better than subsonic, given the ammo I can afford.

-TL

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