About .22 LR conversion kits on AR's

M

Max013

Inactive
At a local sporting goods store, there were a few CMMG .22 LR conversion kits for AR-type rifles on the shelf. (Simply switch the bolt carrier and magazines and, viola, and you got yourself a .22 plinker that won't break the bank!) My question is how much more wear & tear will this cause on my barrel (i.e. rifling erosion)?

I've heard that AR-15/M4-type rifles have a barrel life between 10,000 to 20,000 rounds depending on the .223/5.56 load, but because of the cheapness and availability of .22 LR's my guess is that I will go through a lot of rounds with it. Experiences and input anyone?
 
An rifle barrel will loose accuracy primarily from throat erosion. The hotter the round, the worse the erosion and the shorter the barrel life. A .22LR will cause very little throat erosion when compared to a 5.56mm round, IMO.
 
You won't really wear the barrel. The .22LR is much slower than .223, and with less pressure and heat, the barrel will last a good long time.

The two areas where you might have issues would be gunk buildup and accuracy. The .22LR is a REALLY dirty round, so you will be very likely to gunk up your gas tube if you shoot a bunch of it through the rifle without including a couple rounds of .223 every couple magazines in order to flush the junk out of the gas tube. You will still have to clean the upper and lower though; they will be dirty. The accuracy will be an issue due to the twist rate of the barrel; a .22LR round prefers about a 1 in 16 twist, the AR-15 can be anywhere from 1 in 7 to 1 in 12 (although it seems most nowadays are 1 in 9 or faster twist). That will overstabilize the bullet and it will lose some accuracy. Now, the Aguila SSS .22LR round is very heavy for the caliber and this twist rate is just about right, so if you want to shoot those rounds (they will cost a bit more) you should be just fine.
 
If you want to shoot 22 from your AR just get a dedicated 22 upper.
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+1 on this. I have a CMMG dedicated upper. It is flawless in ~8k rounds. With federal bulk .22 ammo it shoots 2" groups at 50 yards.
 
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