Most quality bcg i've found for the 7.62x39 - FailZero 7.62 X 39 Bolt Carrier Group (BCG), No Hammer

I feel that these BCG's are the slickest highest quality NiB coated 7.62x39 option out there, and never assume other NiB coated ones should be considered to be the same quality as these! However, I feel like there's a strange collision in dimensions in an AR in this caliber and I will try to share what I've had to learn the hard way. Bear with my numbers, this may help you. GI spec I found for the bolts overall length is 2.800" center of spec. GI firing pin from the front of the flange that stops its forward movement against the back of the bolt, to the tip of the pin is 2.707" center of spec. I've measured random Enhanced firing pins to be 2.717"-2.720". I've found typically from the front of the bolt to the face of the bolt that the firing pin protrudes from is usually about .124" deep. Lets say for example that you buy a BCG and measure all the parts, and the bolt is 2.800", the enhanced firing pin from flange to tip is 2.717", and the bolt face depth is .124". (2.800"-.124"= 2.676") then take 2.717"-2.676"= .041" calculated firing pin protrusion. I dug up some old specs from across the pond for the 7.62x39 cartridge. Required pin protrusion said .047"-.060". Doesn't add up to me, (also fought many failures with different setups) so I now machine the back of the bolt down to get at least .050" firing pin protrusion and I've never had a light primer strike since, even with stock hammer springs. I believe that the bolt overall length spec for a 7.62x39 AR should NOT be 2.800". I have since cut every one down, and they will eat tula and other hard primers for lunch. Hope this helps somebody, this should always be checked on this setup.