300 piston upper

[Fudmottin]

This seems like a reasonable place to ask the question. Do AR piston systems work like on the FAL where you have an adjustment valve that vents to atmosphere?

Since the OP is interested in avoiding blowback of crud from a suppressor, does a piston system actually help with this? I would expect crud doesn't like to make right angle turns.

Finally, is there any real evidence that the piston design is more reliable than direct impingement? I'm sure it is cleaner for the action. But the usual reliability debates between ARs and AKs point at the gas system and heavy bolt without bothering to look at the fact that the 7.62x39 case has quite a bit of taper vs a straight wall that is longer.

Wouldn't a standard AR chambered in 7.62x39 be just as reliable as an AK? Have any MTBF tests been done?

The shorter case on the 300-221 should mitigate the problems that fouling cause.

[redtazdog]

When shooting with a can the piston and the gas upper both get
very dirty because the blowback crap comes from the barrel not the bolt/gas tube.
The action noise is the same with both piston and gas upper when using a can.
The gas uppers are quieter because they dont spit more noise out of the
gas block like a piston upper.
The only thing i have found to be better about the piston upper is it
does stay cleaner in the action when not using a can.