One thing we had to do to get the LAW folder to work with the PWS upper is to bore out the back of the MK107 bolt carrier to fit the LAW bolt carrier extension. The extension is dimensioned to work on a mil spec bolt carrier but since the MK107 is a piston gun, the bolt carrier is not made to Mil spec. The bolt carrier is made out of a really hard and tough material and was a bitch to machine. Our gun, despite the long stroke adjustable gas system was having some reliability issues with certain ammo. We had double feed issues because the bolt was overrunning the next round in the magazine. Sometimes the extractor would come off the case rim as well causing failure to extract. We think that this was caused by the Noveske muzzle device creating more back pressure on the gun and excessive pressure in the gas system than what it was tuned for. Instead of just adjusting the regulator, we used a stiffer Sprinco “Blue Spring” with a full length Odin Works Stabilizing Brace Pistol Buffer Tube and a heavier Spikes Tactical ST-T2 Heavy Buffer to slow the cycle down for more reliability and less stress. The ST-T2 buffer is filled with heavy tungsten powder so it does not rattle and has some damping capability to possibly reduce bolt bounce.
