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Posted: 6/29/2015 4:23:28 PM EDT
  Generally if a bolt catch breaks it will be on the outside where you depress it. Im a POST certified armorer and this is just baffling me. Im using a CMMG LPK, CMMG buffer/spring. and next level armament .308 BCG. its 4140 steel. this competition series of .308 rifles never had any issues until the BCG. It broke the bolt once, I replaced the bolt with a different manufacture and didn't replace the carrier. I also reluctantly shaved down the hammer so that even with the upper receiver off if you dropped the hammer it couldn't touch the bolt catch. Just in-case something was out of spec I wanted to eliminate that variable. Im almost 100 percent certain its something to do with the bcg. Notice the fault line and the way it broke off. Its looks as if its the bolt face hitting it and cracking it. Once understandable. twice? unacceptable.
Any thoughts? Picture with link below http://postimg.org/image/4fyr315mp/ 
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Pull all the way back on the charging handle, the get your finger in front of the bolt and push the bolt back more.
The front face of the bolt should stop/max out rearward 1/8" to 1/4" in front of the back of ejection port window edge. If the bolt face is coming back past the back of ejection port (ejection port with a spring loaded cover on it), then you have either the wrong receiver extension, buffer, or buffer spring in play. As for if the bolt face is stopping at the correct distance in front of the back edge of the ejection port window, either the recoil spring is weak as hell, the gas port is too large and the rifle is over functioning (no back of stroke stall, but instead the buffer is bouncing off the tube and being sling shot forward instead), or the batch of bolt catches were not correctly annealed after they where initial heat treated instead. To add to this, the bolt impact mark to the bolt catch does seem to be greater than normal, with maybe the bolt catch springing up higher that it should be to start with. Or worse, the hammer bottom releif cut not high enough, bolt catch channel slightly back that where it should be in the receiver, and it could be the hammer crashing into catch instead that is snapping the catch. P.S, Where did you get your POST certification for the SR-25/Mk 11 Mod 0/M110? |
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