.22lr barrel length

[crazykg85]

This question is really for the guys that have tested the muzzle velocity with various .22lr ammo.

I have been trying to do some research and have not had any luck on getting a decisive answer on the subject. Some people at other forums have been saying that 16 in barrels in .22lr are getting maximum velocity out of whatever rounds they are using. However, I also read they various manufacturers don't get the velocity that is stated on the ammo box at the barrel- some are off by up to 200 fps at the muzzle. Let me say that semi-autos will get less energy than any closed bolt firearm out of the round at the muzzle because of the way the actions operate.

Now on to my question(s). At what barrel length will someone get maximum velocity out of the round? I know the variables are how fast/slow the powder burns and the action of the firearm.

Has anyone been able to test various ammo types at different rifle barrel lengths?

Does having a barrel that is longer than maximum velocity hurt accuracy (assuming that the rifle and round are accurate together)?

Is barrel length why the 15-22 PC model is "supposed" (some have made claims that it is not as accurate as was advertised) to be more accurate?

 

[rraisley]

Normally, longer barrels (up to a point, probably) give a bit more accuracy than shorter barrels (certainly more than very short barrels). As to maximum velocity, as you might expect, it varies a bit depending on the ammo used. Ballistics by the Inch is a good reference, both for .22 and for other rounds. While I wouldn't say that the 15-22's 16" barrel might not always be the optimum length, it certainly isn't far from it, is the minimum legal length, and that makes for a compact and sporting rifle.

 

[Kayback]

Ballistics has a lot to do with the internal dimentions of your barrel and chamber, as well as the batch of bullets you are using. Not every batch is exactly identical in composition of primer and powder. The cases may be slightly different, the lead compound used in the bullet maybe different....

Especially with cheaper bulk ammo. There is a reason why Federal 550 is $0.03/round and something like Ely match is $10.

The length of a barrel actually has very little to do with accuracy. There are plenty of other things that are more important. One is the alignment of the chamber to the barrel. Especially with something like .22LR which has a head bigger than the case getting correct alignment is tricky. The 15-22 PC has a competition level chamber. This is one reason you can't use some ammo (CCI Stingers) in the 15-22 PC.

A longer barrel will not degrade your accuracy, it will only degrade your muzzle velocity.

This means the bullets won't have the same trajectory as a barrel with a more optimum length. But each and every round from your gun will be the same. Degraded compared to other rifles, but similar from shot to shot.

A lot of manufacturers use test barrels to get velocity information. Those hardly ever work like real gun barrels. They are completely sealed units. An actual firearm, like you said, has varying actions that will be in operation at the same time as the bullet is accelerating, sapping some of the energy.

Something as simple as the style of rifling also makes a difference to velocity.

As a complete package the 15-22 is not an "accurate" rifle. If you want that you are barking up the wrong tree. You need to be looking into Anschutz for super accurate, and things like the CZ or BRNO family for decently accurate. Even the miniature Cricket rifle will beat the pants off a 15-22. The 15-22 is for rapid fire "acceptable" accuracy. It can produce tight groups, but not overlapping cloverleaf patters.

One of the reasons a longer barrel has historically been more accurate than shorter ones is simply the sight radius. It allows fore more precise aiming. The distance between the front and rear sight means the adjustments can be finer. With an RDS or a scope, this is more or less negated. You should expect the same sort of accuracy from a 4" barrel and a 16" barrel. However, the 4" will have a much steeper trajectory, making it "harder" to shoot at unkown distances, simply because of the velocity drop off.

16" is a good compromise for .22. It is around there where most rounds hit their maximum speed. Much more and you are wasting weight and maneuverability. Much less and you are risking jail time without registering your SBR.

 

[OldEagleEars]

Kayback has provided a wonderfully informative post and I thank him for it. But I would like to throw out something for other .22 caliber users to think about. Monday I purchased a Rock Island Armory 1911 chambered in a new Armscor round called the .22TCM. It's based on a necked-down 9mm cartridge and carries a 40-grain jacketed hollow-point projectile. Right now only Armscor makes it and the factory load spits that little thing out at a rated two-thousand (2000!) feet-per-second. Yes, it's a .22 and yes, it's a pistol round for now; but give a thought about what kind of device a 15-22 chambered (and all the other stuff) for that round would be. Armscor refers to it as a "Micro-Mag" and I don't think that's an unfair description. When fired, it produces a spectacular fireball and a thunderous report (I freaked the others at the range when I shot it) but in the 1911 platform presented less recoil than a standard 9mm; almost like a .22 mag in a lightweight revolver.
This cartridge may be the future for serious .22 caliber hunting and some of us have fantasized about CQB carbines and super-concealable machine pistols for high-value target protection, but it's development will depend on guys like us accepting and using it in normal shooting situations. Keep an eye out for it; it just might be the ultimate twenty-two!

 

[photoracer]

All .22 LR ammo is tested in 24" test barrels. That produces more velocity than a shorter barrel but the velocity only goes down a little until the barrel is below about 16". From other info it has been said that in all versions of .22LR ammo the powder is fully burned in the first 16" of barrel although that varies by the powder used, so some are fully burned in less. As a result once you get to barrels below 16" the velocity goes down by a greater rate as the barrel gets shorter.
Out of 4-6" barrel all SV and all high velocity ammo is subsonic (depending on altitude). Hyper velocity ammo is still supersonic at that length. Out of a 16" rifle barrel all SV and some lower velocity HV ammo is still subsonic, at least at sea level. Some HV ammo will go SS depending on slight differences in gun action or powder levels. You can tell by the sound.
As for the .22TCM you will not find that being shot out of a gun like the 15-22. Way too powerful for a polymer upper receiver. You will only find that round in either pistol caliber carbine conversions, AR conversions or dedicated guns. However I doubt it would be that popular considering the FNH 5.7x28 is about the same speed and power. And you can get more bullets in the mag with that than you could with the .22TCM.

 

[ukm@p]

Is their a way/company that can tune/modify the 15-22 into a much more accurate rifle or is it the core design that hinders this? Has anyone here been able to get theirs to do super impressive groups at say 100yds as I would love to get mine to print 1" groups at this distance..

 

[Kayback]

It sounds very much like the .224 Boz. Initially that was a 10mm necked down to .223, but the latest development of it is a 9mm necked down a 2200fps and 50grain....

 

[Majorlk]

Is their a way/company that can tune/modify the 15-22 into a much more accurate rifle or is it the core design that hinders this? Has anyone here been able to get theirs to do super impressive groups at say 100yds as I would love to get mine to print 1" groups at this distance..

I doubt the veracity of anyone who says them get 1 MOA out of a 15-22. Out of a all-steel bolt action, yes. Out of the 15-22, nope. Trying to make it a 1 MOA firearm is an exercise in futility. If you want a 1 MOA match gun, buy one and be prepared to pay for it!