08-10-2020, 05:46 PM
Take the upper off the lower and put the BCG in the buffer tube. Push the BCG all the way back into the buffer tube until it stops. There should be a minimum space between the gas key and the lower receiver two American quarters thickness.. I have never seen a spec for the space between the mag catch and bolt face when the BCG is in full cycle all the way back, but there should be at least .120-.125 minimum space or better in my experience.. Out of spec buffer tubes, poor installation, weak or using the wrong recoil spring will show after doing this test common test..