Quote History Quoted:
I haven't run the new Mk1 series rifles with the adjustable gas settings but I do have one of the original 300 Blackout 9' uppers.
I have used my AAC 762-SDN-6 extensively on the MK109 upper and can tell you that there's a ton of fouling that makes its way back into the upper through the gas tube. Piston guns in general still suffer from blowback just like a conventional DI gun but the PWS fouls worse than other designs in this regard, in my opinion.
View Quote
You found this only to be the case with their 300BLK variant or you think it is the lack of adjustable gas? I am running a MK112 with a Surefire FA556-212 and, while I do have the standard fouling, I'm not seeing anything near as much as my Daniel Defense. On mine, it is just the bolt and a small part of the carrier, in which receives the fouling.
Currently running mine with a red spring and H3 buffer as well, and have it on position 4, for my adjustable gas setting.