Thoughts on this new bolt? HM Defense

[ABNAK]

http://www.hmdefense.com/html/ar15_parts.html

Smaller cam pin diameter, and a "socket" rather than a hole all the way through the bolt. Supposed to prevent fracturing at the cam pin hole.

[MegademiC]

http://www.hmdefense.com/html/ar15_parts.html

Smaller cam pin diameter, and a "socket" rather than a hole all the way through the bolt. Supposed to prevent fracturing at the cam pin hole.

Interesting concept. Assuming cam pins don't really break (i havent heard of it as an issue) this may be a good move.
Do quality bolts tend to break at the hole or is it a cheap part issue? I have yet to break one and the only one ive seen was a NiB with broken lugs.

[Renegade]

http://www.hmdefense.com/html/ar15_parts.html

Smaller cam pin diameter, and a "socket" rather than a hole all the way through the bolt. Supposed to prevent fracturing at the cam pin hole.

Solution looking for a problem. I shoot Hard Use(CMAG dumps, etc) Full Auto for decades, never broke a MILSPEC bolt.

[SDSwoll]

Seen it happen a few times, it will eventually happen even with quality parts. In-spec bolts it usually takes many thousands of rounds, cheap parts it happens quicker. IMO solution looking for a problem as most who buy quality bolts will not shoot enough rounds to experience it.

[1168]

Solution looking for a problem. I shoot Hard Use(CMAG dumps, etc) Full Auto for decades, never broke a MILSPEC bolt.

Milspec bolts certainly do break. I suspect one of the reasons civilian shooters rarely see it is because most guys racking up round counts seem to be shooting 55gr or 62gr .223, and many are shooting it from middys. Even a lot of the commercial “5.56” seems a little light.

Run enough M855A1 through a .gov M4, and bolts do break, eventually.

I try not to worry about it too much, so this bolt probably isn’t for me.

[Renegade]

Milspec bolts certainly do break. I suspect one of the reasons civilian shooters rarely see it is because most guys racking up round counts seem to be shooting 55gr or 62gr .223, and many are shooting it from middys. Even a lot of the commercial “5.56” seems a little light.

Run enough M855A1 through a .gov M4, and bolts do break, eventually.

I try not to worry about it too much, so this bolt probably isn’t for me.

While I never broke one, I never meant to imply they never break, just not often enough to need a special bolt.

Can't speak for 55/62-223, I only user M193 or M855 out of an Factory M4 or MK18.

Have broke a few 7.62x39 bolts though.

[ABNAK]

Going back to Stoner's original design, I wonder why it was ever necessary to have a cam pin hole all the way through the bolt? Would seem to be creating a potential weak point, no? i.e. there's nothing the cam pin interacts with on the far side of the bolt.

[jpaul]

I’m the first to admit that I don’t know nothin about nothin, but I would think the cam pin going through the bolt making 2 points of contact is a good thing. As the bolt is being rotated and pushed & pulled in or out of the carrier, those 2 points should help keep the stress applied distributed over a larger area. Maybe even helping the bolt to maintain alignment w/ the inside of the carrier as it’s traveling to & fro?

Like I said, I’m not a scientist or engineer, but the traditional design makes sense to me.

[Ned Christiansen]

I thought it was a great idea and I have one for testing this training season. My first impression is that quite possibly, "this solved it". It does still give two points of contact. Looking at it I believe that given good materials and processes, this design ought to be way less crack prone.

[1168]

While I never broke one, I never meant to imply they never break, just not often enough to need a special bolt

I think I misunderstood your earlier post.