Well all this AR piston talk, my AK fetish, and the fact that the legislature of Colorado is hell bent on pushing through an AWB this year prompted me to order a PWS Mod1 assembled lower last night. The MK116 upper will be purchased later. Considering my satisfaction with my 516, I certainly don’t need it but I have always wanted one in 556 (I have the 308 rifle) and it will be interesting to compare the long stroke to the short stroke systems….