I think I have solved my over gassing problem. I've been fighting this ever since I got my RFB. After getting it back from Kel-tec with new gas and barrel everything except Prefecta and American Eagle .308 150 gn was over gassed. All 7.62 were over gassed. Talked to Kel-tec and tech told me that I should be in the B+8 range for 7.62. I was over gassed with cap almost off. Piston was still very tight after many trips to range. I removed the 3 gas rings on piston. Now all 308's and 7.62's are in the B+7 to 10 range. Now I'll try my suppressor and see how it works. Before I was B+25 with .308 and now around B+9. Still think it will be over gassed at B+ 40, but it's worth a try.