I'm going to SBR my 15-22 and curious to hear latest thoughts on the best length. I read everyone saying 4.5 inch for subsonic but some have had issues so did 10.5. For the latter, do CCI standard velocity still stay subsonic? For 4.5 inch, is it reliable? Thanks.

CCI SV will stay subsonic in a 16" barrel... I use them all the time on my non-SBR'd 15-22.. Never a sonic crack, even in winter.

Thus, the CCI-SV will stay subsonic in a shorter barrel as well.

The point of going to a shorter barrel is (amongst other things) having high velocity ammunition (which is often more plentiful, and less expensive) be subsonic.

Since the 15-22 is a blowback, a 4.5" barrel might be a bit too short without lightening the bolt or the spring (for example, the 15-22 pistol has a lightened bolt...).

7-10" should do well without any other modifications.

Depending on what your reasons are for going the SBR route, you might consider an Innovative Arms integral suppressor; they cut the barrel to 10", pin and weld a 16" suppressor. That means it's subsonic for even high velocity ammo, the length is the same as your current rifle, weighs about the same as your current rifle and does NOT require a form 20 to cross state lines. So, it's still one stamp (Form 4 instead of a Form 1).

The downside of the IA integral is that you can't change the handguard, and you can't reuse the suppressor on another firearm (except another 15-22...)

HTH...

12.5 inch for mine.

That's UK legal barrel length min so that's what I have.

I'm not too worried about HV / Sub noise levels as I also have a sound mod to switch out as and when I feel like it.

What I did notice was an improvement in group size after the barrel was chopped, not sure if that was the quality of the guys work who cut and recrowned it or just a result of a shorter barrel.

Either way, I'm a happy plinker.

Rob.

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Utrinque Paratus