Broken Bolt

[deadelk]

My brother bought a used Bushmaster AR-10. We field stripped it and discovered the the bolt stem was broken. I have found a little info online and was wondering if any of you were familiar with this problem and your experiences. Thanks.

[bkb0000]

bushmasters have a rep for some known reliability issues.. while not "common," bushmaster doesn't HP/MP test their bolts, so this is bound to happen. just get a new bolt- LMT is basically the standard aftermarket bolt upgrade. i would recommend buying a complete full-auto LMT bolt carrier group- $130 for complete peace of mind.

read the stickies in the technical forum

[Heavy Metal]

Note: This is a .308 AR-10 type rifle.

A standard AR bolt will not work.

[bkb0000]

my bad, disregard. i know nothing about beyond-556 stuff.

[constructor]

Not specifically Bushmaster but, there are some large companies using plain 8620 cold rolled steel to build bolts from. Carriers are usually 8620 but bolts should be Carpenter alloy 158.
From what I hear there are only 2 companies that actually make bolts using the correct spec of Carp. 158. One of those companies only makes 5.56 bolts for specific DOD contracts mainly Colt and FN.
The old scratch it with a file trick does not work. MPI does not mean it's 158 either just that is has been inspected.
Personally if I was shooting a 308 I would buy Armalite bolts and carriers.