Are BCG universal?

[SAnd]

Could you do the reverse?Use the bolt from the sear blocked lower in another?

Yes you can use a bolt carrier made for the Colt sear blocked lower in/with a non sear blocked lower.

[hghclsswhitetrsh]

Not if its for a dedicated left hand upper bcg.

[zteknik]

Yes you can use a bolt carrier made for the Colt sear blocked lower in/with a non sear blocked lower.

Thanks,that's what I was thinking-just not real sure.

[zteknik]

Not if its for a dedicated left hand upper bcg.

That would need a completley different unit,I doubht one can easily modify it to fit.

[Dalendenver]

As long as they are the same caliber. 223 / 5.56 yes. 5.56 to 6.5, 6.8, etc. Defiantly not.

Caliber only applies to the bolt, not the BCG. You can put any of those caliber bolts in any BCG. I have a 6.8 AR with a M16 BCG and a Stag 6.8 bolt. They are in a Palmetto State Armory upper.