Broken bolt on psa upper

JohnnyD · May 8, 2016

A while back I traded a buddy a ar15 and today while he was shooting he broke the bolt in half at the cam pin hole. From what I've read this is common enough but is there anyway to avoid this happening? Any common cause of this? Also if anyone is selling a bolt he's looking to buy thank you.

rick benjamin · May 8, 2016

http://www.bravocompanyusa.com/BCM-AR15-Bolt-Assembly-MPI-p/bcm-bolt-assembly-mp.htm
http://palmettostatearmory.com/ar15-complete-mpi-bolt-assembly.html
http://www.surplusammo.com/bolt-carrier-groups/
http://www.brownells.com/items/ar-15-bolt-assembly.aspx
http://www.joeboboutfitters.com/Rock_River_Arms_5_56_223_Bolt_Assembly_No_Carri_p/rra-ar0034asy.htm

JohnnyD · May 8, 2016

Thanks for the links. I've been looking too and they're not badly priced saw some stripped ones for as low as 35 bucks

IronMonster · May 8, 2016

I would guess that one was improperly heat treated. If that is the case nothing would have kept it from breaking, it would have eventually. If you suspect it is a PSA orginal part I would say give them a call, If they had a batch with botched heat treat they would know it and would might send you out one gratis.

Member 34319 · May 8, 2016

I've broken one so far. Taught me to keep spares now.

Lube helps.

Basically this is the stress point when the lugs start to turn. The cam pin hits the slot in the receiver, putting stress on this portion of the bolt to spin the bolt and lock the action.

Lube, and or if you really want to, you can purchase a rolling cam pin.

<broken link removed>

However I would add that @IronMonster is right, it was probably just a bad bolt. As mine was too with added wear.

JohnnyD · May 8, 2016

Thanks for the info guys. Yeah not 100% sure if it's a psa part. I got it from a member on here a few years ago then traded it to a buddy of mine and got a killer deal out of it. I'll find him another and might buy a spare for my Anderson as well. He's talking about maybe just buying a nickel boron bcg so we'll see. One thing I did read was usually guys had problems with them getting stuck his just kinda fell out he said maybe the lugs hit the chamber causing it to break? Not sure oh well just feel bad for the guy he hasn't put many rounds through it .

v0lcom13sn0w · May 8, 2016

bubblegum

PiratePast40 · May 8, 2016

Was just reading a thread on ARF about having spare bolts on hand. Had no idea that bolt failure was that common. Is it common with MPI and HP tested components?

JohnnyD · May 8, 2016

From what I've been reading it's less likely with the mpi tested ones but guess they all break

IronMonster · May 8, 2016

Its a machine, That is the weak part in the bolt. They do break there.

Is it common? No, I would not say its common. The vast majority of AR bolts, probably 9999 out of 10,000 will never break.

But you might be the one guy

And yes I would say it is less likely to happen with a quality bolt, not necessarily because of anything other than they are quality checked and have to pass inspection.

Velzey · May 8, 2016

Call Palmetto up, tell them hey my bolt head broke in half.. I've Never had a problem with your stuff in the past, etc etc etc
5 days later your entire new bolt assembly comes!

I lost one locking lug on one of their bolts a few years ago, they took care of me !

As Ironmonster said, it's heat treated, yah they break on occasion.

There is a certain machine shop in Clackamas that makes 1000's of AR bolt carriers, and bolt heads (pssssst is a secret but they make them for about 10 different manufactures)

. Then they send them to Met Tek heat treating in Clackamas.. I've seen baskets of 3000 bolts going into and out of the heat treat ovens.. Maybe that bolt head was the very corner bolt in the basket that didn't quite get all the attention it needed in the oven???

Anyhow PSA will take care of you!