just_john Wrote:Turned out, the bolt carrier was chrome lined and the thickness of the plating was inconsistent where the bolt neck went thru the smaller aperature in the carrier and was briefly sticking in place. Replaced the carrier with a non-plated one and all was well.
All mil spec carriers are chrome plated on the inside..This is why many nitride carriers are out of spec because they are machined with the same specs as chrome lined and don't compensate for the chrome thickness..If the bolt was also chrome lined, then an excessive tight tolerance could occur..
The tolerance between the carrier I.D. boat tail bore and the bolt tail O.D. is .0019 to .0021..
Eye_guy Wrote:The bullets (spent or live) will jam in the chamber to the point that the charging handle alone cant remove them without excessive force.
If this occurred after charging a round, then there is more going on than just a gas issue..
Could be the barrels are getting clocked in the uppers (impeding bolt rotation and ejection), chamber problems, upper/ barrel extension tolerance issues, etc..