BCM extractor upgrade kit and the Alexander Arms Overwatch - Didn't work out for me..

[Bill Alexander]

The Grendel/Beowulf extractor has a slightly different geometry to a 5.56 as the case has a larger rim dimension and allows a more positive engagement. The problem with the extractor jumping the rim is largely removed by the heavier rim so it is not necessary to place the extractor under as much force. This has two benefits, The extractor itself is not flexed as severely so this area of failure is removed and the extractor spring itself can be lighter. Using a lighter spring with less mechanical compression extends the life of the spring. The downside is that the bigger rim demands a larger extractor cut. this can weaken the extractor unless it is reinforced at either side of the extractor flag and this in turn tightens the tolerances between the extractor and the barrel extension during feeding.In instances where the vendor is not in control of the parts or where they are negligent of such consideration a binding condition can occur.

Anyone here able to tell everyone the tolerance stack on the barrel extension minor?

Turning to the extractor pivot pin this cannot fall out of the bolt during use as it is retained within the carrier bore.