I built an AR pistol once. Was a fun gun. Accurate, not so much. Then again, it was a build for a buddy, so I never installed a sig brace. I told him to get one. He never did.
Without the brace, when trying to use a scope, the poof of air was just annoying. Plus I did a standard build instead of lefty, I have to shoot lefty. in SBR trim it was great though, however without a stamp could cause some issues...
Guns are a hobby of mine.