Blank firing adapter

[Juggernaut762]

In reference to the two types of clamp on blank firing adapter for ARs that are commonly available online (military surplus BFAs), it is my understanding that the red BFAs are for 20" barrels with rifle length gas systems and the yellow BFAs are for 14.5" barrels with carbine length gas systems. The difference between them and why makes sense to me so my question is which to use for a mid-length gas system and does barrel length have a significant impact on this as well due to difference in gas port to muzzle for different gas system lengths and barrel lengths?
Thanks.

 

[Renegade]

Yellow was for 16, it works in 14.5 too. originally there was only rifle and carbine length.

There is also the Hollywood BFA, which is hidden inside the FH.

 

[Juggernaut762]

Thanks. I've got a 16" and an 11.5" both with mid-length gas systems and a 20" with rifle length gas system. I'm wanting to use it for force on force training and like the visibility factor the GI clamp on BFAs provide, plus I'm lazy and don't want to take my flash hider off and back on just to shoot blanks.