I'm busy with our (NON USA) process of cutting the barrel on my 15-22. I want to make it a Mk18 style gun so looking at 10.5-10.3" length.

Is there any drawback to doing this?

The idea is to get my suppressor as close to flush mounted with the hand guard as possible.

That length barrel gives me no issue whatsoever, even with subsonic ammo. When I went shorter, a 4.5" barrel, I had issues with subsonic ammo. Granted HV stays subsonic in such a short barrel but the rounds are still louder than subsonic & to me, if you are gonna shoot suppressed, you want as quiet as possible.

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I found 10" is a happy middle ground from 4.5" and factory 16".
Shoots everything and is well balanced