**school me on Boosters/Pistons**

[jba6511]

So with a fixed mount on a 9mm AR you do not need a spacer? I thought the threads were longer on ARs requiring some kind of adapter/spacer but I am a newbie trying to figure this out. Thanks

 

[Laxguy59]

So with a fixed mount on a 9mm AR you do not need a spacer? I thought the threads were longer on ARs requiring some kind of adapter/spacer but I am a newbie trying to figure this out. Thanks

On a 9mm ar you will need a fixed mount. You wont need a spacer since there is nothing that will contact the actual crown. In most cases spacers are only to prevent threads from messing up o rings on suppressors that use those(like the sparrow).

 

[jba6511]

Excellent, thanks for clearing that up.

 

[sovietak474u]

On a 9mm ar you will need a fixed mount. You wont need a spacer since there is nothing that will contact the actual crown. In most cases spacers are only to prevent threads from messing up o rings on suppressors that use those(like the sparrow).

This. My fixed barrel mount is long.