Is there a hazard in using one bolt/carrier/ch between different uppers? My Bushy has about 1500 rds through it, and I plan on using the bolt group with an as-new Colt upper. I recall reading about potential issues with such a swap, but can't remember the details, or find the references.
Primary concern is safety issues, then reliability, then accuracy.
Primary concern is safety issues, then reliability, then accuracy.