I bought a brand new RFB and luckily I live next to kel Tech. Took it out and it blew two magazines apart I didn't know if it was something I was doing adjusting the gas or I will say I was using the oldest cheapest ammo sitting around LOL. Apparently it was blowing through the primers with a firing pin .I took it to keltech they did a whole bunch of stuff on it and gave it back to me the next day! Very nice people that were helpful. I recently took it hunting in Georgia and did a bunch of target practice up there and it's amazing! I will say it is a heavy rifle outfitted way I did. But I had not one issue and the gun shot amazing using 1990s Pakistan army 147 grain lol. Really cool gun. Great people at keltech. I was skeptical especially after my incident LOL but now I'm a Believer. I heard the rfbs get smoother after they are broken and as well.. and I have heard other people having issues here locally. But I've had over a hundred rounds through mine this weekend and love it! I picked up a newer gen2 PSA ar10 and after shooting these side by side I have to do a whole bunch to the AR10 to achieve the smoothness of the RFB hopefully lol in fact after a few shots and hurting my shoulder I said screw this AR10 stuff I know there PSA is over gassed..but anyways yeah I love my RFB even after a couple issues and Kel-Tec was very very good to me! It was probably even my fault with 180 grain 1980s cheap ammo and not being set right on the gas. But you live and learn