AR-15 BCG Questions

**Gunowner99** · June 22nd, 2016, 10:25 AM

All builds I have done thus far have had a preassembled upper with BCG and charging handle. All .223/5.56.

I have been looking at uppers with no BCG or charging handle.

Now I know charging handle is pretty self explanatory however the BCG is not. I see M-16 BCG. I see AR-15 BCG. I see fully auto BCG. Can I drop any of the 3 in my 5.56 upper with a charging handle or is there some variations I need to be aware of? Also I hear you need to headspace them (BCG and upper)? What does that entail?

Just curious as I may give it a try.

**ExFlyinguy** · June 22nd, 2016, 11:36 AM

Short answer: They will all work.

**dkf** · June 22nd, 2016, 11:38 AM

The "M16", "Full Auto", "AR15 semi" refers to the carrier. The M16 or Auto carriers are not cut at the rear of the carrier to reduce weight like the semi auto carriers are. I always get the M16 carriers and adjust buffer weight if need be. The extra weight can help the rifle run "smoother".

The headspace is supposed to be set by whomever chambers the barrel. The bolt is supposed to be made within a certain tolerance (which is not a loose tolerance) so it can work with any barrel with a chamber cut properly. You can get go no go gauges to check headspace if you want. I usually can get a good idea by looking at the spent brass if something is wrong. A good BCG that I usually buy that is priced good is the Spikes Tactical.

**morpheus6d9** · June 22nd, 2016, 12:23 PM

i have aim surplus , spikes , ares armor and and psa carrier with a no name bolt they all run just keep em lubed

**Fortytwo** · June 22nd, 2016, 04:44 PM

They are interchangeable, most of the times... Two of my mid-length PSA uppers have had troubles to consistently cycle lower-powered Eastern European steel-cased ammo. Switched them to semi-auto bolt carriers and they run well since on all types of ammo I feed them. That 1 oz of weight difference between the semi- and full-auto profile carries sometimes does matter with certain gas system/ammo/buffer combinations. My mid-length Troy upper never had such troubles with full-auto BCG, for instance.

Also, I believe in some locales in communist states the full-auto/M-16 bolt carrier is considered a "machine gun part" and is outlawed.

**Gunsnwater** · June 22nd, 2016, 04:54 PM

If I can recall correctly don't use a stepped hammer with a full auto carrier. I'm sure somebody will correct me if I'm wrong. I'm just not energetic enough to google foo it.