Most of the time, if you buy MilSpec parts you're ok. I usually buy the same bolt carrier as my upper
I'm sure you can have it headspaced if you wanted though after getting one.
Yeah but how difficult would that be finding someone who knew what they were doing?
I'm sure there are lots of gunsmiths familiar with the AR.
Honestly though, I've never heard of anyone having to do that. Just get a good milspec one and you should be good
It is not a marketing ploy at all BCG's are are to get and so there is a shortage and we don't have them.