Full auto/ Semi Auto BCG(AR)

bambambam

I was searching online about the differences between the two. It seems the full auto version doesn't have as much metal milled away in the rear.

I was reading that the full auto BCG's were being installed by Colt into semi auto versions because they were more robust.

Did I comprehend that correctly? Can you put a FA BCG in a SA gun & have it function properly w/o mods?

tsr1965

The full auto BCG will function in semi-auto mode, just fine, and not go into full auto...unless there are some other parts installed. There are several other's that use the M16/M4 BCG, in their AR's also.

Those other parts would be the Selective fire control group, and an auto sear. Even with the fire control group, and the FA BCG, the AR-15, as a general rule, will not slam fire, as the hammer, when riding the bolt carrier, back into battery, does not posses enough energy to set off the primer. That is where the auto sear comes in, as it delays the hammer falling, untill the bolt is into battery.

So yes, your semi-auto AR will function perfectly, with a full auto BCG.

Best

Txs

What's referred to as a full-auto BCG these days was originally the standard item for both semi and select fire AR's.

To increase the difficulty of converting a semiauto rifle to full auto, over the years Colt made numerous changes to their BCG's which involved removal of metal. Reliability issues related to lightening of the carrier began to be identified and Colt pressured BATF to allow their older, heavier design to be used in rifles with semiauto lowers.

This finally came to pass (at least) 6-7 years ago. All Colt Defense AR's now leave the factory equipped this way.