So one of my ARs stopped firing! Updated 3/25/11

[saleen]

I have seen that failure many times, and it has predominantly been on Bushmaster bolts run in SBRs or pistols. The shorter guns tend to be a bit more violent, and if you were using full power Q3131A, that just adds a bit more stress.

FWIW, I have never seen this failure on a bolt that has been shot-peened and MPI checked after a HP proof round. I tend to use BCM bolts and have always been happy with what they delivered.

http://www.bravocompanyusa.com/BCM-A...semly%20mp.htm

Del-Ton is another good source, but I've never used their bolts so I can't vouch for them. Overall, however, they have a good reputation for providing high quality parts.

There's really no telling where your original bolt actually came from. It might not even be from this side of the pond.


Saleen

[imanaknut]

Thank you Saleen for that link. Haven't replaced the bolt yet but was considering the one from Spikes, but the one you link to seems as good even if it is the "wrong color".

The sad thing is the bolt in the Carbon 15 goes beyond what most manufacturers to to their bolts, The engagement lugs are rounded which is a major stress reliever. Guessing they worried too much about the lugs and not the rest of the bolt.

Thanks again for the link.

My next question, the Spikes is chrome, like the one that came with the rifle, the BCM is not. Both are peened and MPI inspected. Is the chromed one worth the $10 extra?

[AK-J]

The hard chrome probably makes it easier to clean.

[imanaknut]

After spending money on a really nice chrome replacement bolt, I come to find out that Professional Ordnance used a proprietary bolt, and that the standard AR-15 bolt doesn't work.

I called Bushmaster and found out that one of their upgrades to the Carbon 15 was to change the barrel to be able to use a standard AR-15/M16 bolt. They had a small supply of the proprietary bolts, but ran out quickly as those seemed to be the weak point of the old rifle. They have no plans on making true replacements, but for somewhere between $300 and $400 I could sent the upper in and have it updated.

Unfortunately too is Professional Ordnance also used a proprietary lug on the upper so that a standard AR-15 upper will not fit.

The person at Bushmaster recommended Brownell's as possibly having some in stock, but a call to Brownell's confirmed that I had used up my alloted miracles with them buying Beretta parts, and that they don't have the special bolt.

So now all I am left with is a bunch of parts from an early Pro Ordnance Carbon 15 Type R97...

Oh well, after a run of bad luck with a couple of odd-ball firearms, I am going to stick with the tried and true.

[romak10/63UF]

So after 3000 rounds the ar-15 bolt broke in half ? wow... just wow...

[imanaknut]

After doing a bit of research, it seems the bolt was a common failure point on the Pro-Ord Carbon-15s. Here is why it won't fit:

[matshock]

After doing a bit of research, it seems the bolt was a common failure point on the Pro-Ord Carbon-15s. Here is why it won't fit:

Wow. Round.

[5.56NATO]

Why would they go proprietary?

[imanaknut]

I can only guess that since they were using carbon fiber, which at that time was an advanced material, they wanted to make sure owners only used their parts.

One of the reasons that a "lifetime warranty" is so stupid based on the likelihood of a company being around for a long long time. In this case, Bushmaster bought them out and redid the Pro-Ord weapons to be able to use standard parts.

[Sidartha]

After spending money on a really nice chrome replacement bolt, I come to find out that Professional Ordnance used a proprietary bolt, and that the standard AR-15 bolt doesn't work.

....

Unfortunately too is Professional Ordnance also used a proprietary lug on the upper so that a standard AR-15 upper will not fit.

....

So now all I am left with is a bunch of parts from an early Pro Ordnance Carbon 15 Type R97...

I'd consider breaking the rifle down into parts and see how much money you can get out of it and invest in a Mil-Spec AR.
Since everything is proprietary it has a limited market(as you discovered) maybe die-hard fans will make it less of a loss for you.

BTW, sucks about one broken bolt trashing a otherwise good rifle.

[ready]

Maybe I missed it but you can't just change out the barrel and use a standard bolt to get back in business? What about the lower? Compatible with milspec uppers? For about 250 bucks at BCM, you could be up and running again.

[imanaknut]

You didn't miss it, we didn't discuss just changing the barrel, which is not possible without an adapter. The standard AR barrel is held in by a threaded ring. The barrel in the Professional Ordnance Carbon-15 is pressed and then pinned into the upper receiver.

I am not sure how Bushmaster modifies the upper to accept a standard barrel, and I am sure they are not willing to discuss it.

As for the lower, that I did discuss, and again Pro-Ord decided to also make the mounting lugs proprietary so that a standard upper will not fit into the Pro-Ord Carbon-15 lower.

Really a shame because it is/was a fun rifle to shoot being so light weight yet with almost no felt recoil.

I was thinking about getting a really cheap bolt, and then seeing if I could machine the lugs to something close to the shape of the Carbon-15 bolt, yet still have enough engagement to handle the loads required.

Oh, Sidartha, the Carbon-15 wasn't my only AR, and I believe I have invested in more mil-spec ARs than you could imagine!

[Sidartha]

Oh, Sidartha, the Carbon-15 wasn't my only AR, and I believe I have invested in more mil-spec ARs than you could imagine!

Yea but you could always use another one right?

[ready]

You didn't miss it, we didn't discuss just changing the barrel, which is not possible without an adapter. The standard AR barrel is held in by a threaded ring. The barrel in the Professional Ordnance Carbon-15 is pressed and then pinned into the upper receiver.

I am not sure how Bushmaster modifies the upper to accept a standard barrel, and I am sure they are not willing to discuss it.

As for the lower, that I did discuss, and again Pro-Ord decided to also make the mounting lugs proprietary so that a standard upper will not fit into the Pro-Ord Carbon-15 lower.

Really a shame because it is/was a fun rifle to shoot being so light weight yet with almost no felt recoil.

I was thinking about getting a really cheap bolt, and then seeing if I could machine the lugs to something close to the shape of the Carbon-15 bolt, yet still have enough engagement to handle the loads required.

Oh, Sidartha, the Carbon-15 wasn't my only AR, and I believe I have invested in more mil-spec ARs than you could imagine!

I just read that the headspacing is different as well so even if you were able to grind the lugs down on a milspec bolt, it still might not operate, at least not safely.

[imanaknut]

That is true about the head spacing, and one thing definitely on my check list of things to make sure is right before trying a modified bolt. What a pain, what a shame.

[5.56NATO]

Hoosiers always find a way!