03-11-2013, 03:59 AM
Here are some things that come to mind, in no particular order...
Have you tried other magazines?
Is the BCG traveling free, and unobstructed?
Have you tried lubing the BCG?
Do you have another BCG to try? (Emphasis on the bolt.)
Do the lowers use any Bolt Release add-ons (BAT Lever, etc.)?
With enough time/spare parts you should be able to isolate the issue.
Have you tried other magazines?
Is the BCG traveling free, and unobstructed?
Have you tried lubing the BCG?
Do you have another BCG to try? (Emphasis on the bolt.)
Do the lowers use any Bolt Release add-ons (BAT Lever, etc.)?
With enough time/spare parts you should be able to isolate the issue.