Picked up a ban era Bushmaster A2carbine(IMO cheap-$475) and am torn between keeping it as-is other than threading it, or converting to .300 blackout just because. The only Blackout barrels I'm seeing have F marked FSBs-understandable since most go on flattops. With the different height, how tough would it be to zero to the A2 handle? I'd think it's possible, but don't want to buy a barrel and find out it's a case of "Shouldn't have tried."

Totally able to do, I have done it multiple times. Front sight might sit a little lower in the post than normal, but not a biggie

Thanks, didn't remember if it was shorter or taller due to a stupid moment. Been wanting a Blackout, if I make up my mind this might be the time-although for some reason the NEF Handi-Rifles in Blackout look appealing too, and for what I want it for a single shot would be fine.