AR15 Heavy buffer.

[C185]

Just wondering what advantages a heavy or extra heavy buffer will give over, the unknown weight factory Armalite buffer?

Are they absolutely required in order to have a reliable carbine?

 

[BattleRife]

The heavy buffer was introduced to deal with occasional reliability problems that were coming up in full-auto carbines. They are not at all necessary for semi-auto guns. Some people claim that carbines with 9mm buffers (the heaviest carbine buffer) have less felt recoil than standard ones, but I have not heard any real claims about reliability.