annealed heel

[Bob Seijas]

I don't think it was all a wives' tale -- I'm guessing two things might be responsible: one is that the cracking occurred during initial launcher testing before the need to vent the gas was realized. Another is that perhaps the stronger recoil flattened the bolt lugs/op rod camming surfaces just enough to allow a few thousandths of overtravel. Possible? It might also be bolt wear or tolerance slop that was coincidental with launcher development. I'm just working backward from the answer... they went to a softer steel, a rather big deal... and speculating on why that could be.