Ok, I'm often slow to actually sit down and begin to solve problems. Generally, though, once engaged, I can suss out the cause (if not the resolution) to a problem. This issue has me buffaloed.
Problem: my MGI 7.62x39 "enhanced" Bolt and firing pin sometimes pierces primers on steel-cased ammo.
By comparison, the stock bolt/firing pin combo that came with my Bushmaster 7.62x39 upper doesn't pierce primers, but it fails to ignite a small fraction of steel-cased ammo even though it dings the primer mightily.
Assumption 1: The MGI firing pin is too long.
Actuality: I put both firing pins side x side and assumption 1 was wrong. I measured with a caliper and confirmed that the opposite is true. The stock firing pin is actually .005 longer.
Assumption 2: The firing pin channel on the bolt of the MGI is milled differently such that the shorter pin protrudes farther than stock firing pin b/c the interior has a deeper channel.
Actuality: When the firing pin is fully extended through the bolt, the stock Bushmaster is still a bit longer than the MGI. I didn't measure, but there was a visible difference.
Assumption 3: the MGI firing pin is sharper than the stock Bushmaster firing pin.
Actuality: No, the Bushmaster is a more narrow by a tiny bit.
Question: Why and how could the MGI be piercing primers while the stock Bushmaster firing pin not be doing so? Judging by the measurements I've taken, the Bushmaster firing pin should be piercing primers.
This is not a life or death issue; the MGI bolt/firing pin is a backup, but I'm a fan of consistency. Where else can I look?
Problem: my MGI 7.62x39 "enhanced" Bolt and firing pin sometimes pierces primers on steel-cased ammo.
By comparison, the stock bolt/firing pin combo that came with my Bushmaster 7.62x39 upper doesn't pierce primers, but it fails to ignite a small fraction of steel-cased ammo even though it dings the primer mightily.
Assumption 1: The MGI firing pin is too long.
Actuality: I put both firing pins side x side and assumption 1 was wrong. I measured with a caliper and confirmed that the opposite is true. The stock firing pin is actually .005 longer.
Assumption 2: The firing pin channel on the bolt of the MGI is milled differently such that the shorter pin protrudes farther than stock firing pin b/c the interior has a deeper channel.
Actuality: When the firing pin is fully extended through the bolt, the stock Bushmaster is still a bit longer than the MGI. I didn't measure, but there was a visible difference.
Assumption 3: the MGI firing pin is sharper than the stock Bushmaster firing pin.
Actuality: No, the Bushmaster is a more narrow by a tiny bit.
Question: Why and how could the MGI be piercing primers while the stock Bushmaster firing pin not be doing so? Judging by the measurements I've taken, the Bushmaster firing pin should be piercing primers.
This is not a life or death issue; the MGI bolt/firing pin is a backup, but I'm a fan of consistency. Where else can I look?