Quoted:
Want to switch one of the piston system AR15s over to another rail system that does not use the standard barrel nut. Do really need to use the drive rod spring bushing if the spring itself comes in full contact with the face of the barrel nut?
TIA
View Quote
The drive rod bushing serves two purposes:
1) it provides a seat for the spring against the standard barrel nut, and
2) it provides a stop for the piston's rearward motion.
Not using the bushing would allow the spring to go solid during operation, severely reducing spring life, and possible reduced reliability.
I would talk to AA about this as little specifics have been provided.