Receiver rendered inoperable by broken bolt - what are my options?

[imarangemaster]

I bought a commercial M1 Carbine many years ago (in the 80s) that was caked with cosmolene (which I though was odd...) After I broke it down and detail cleaned it found it was a re-weld receiver. It took some threats, but i got a refund. Now, being older and wiser, I know caked cosmolene is ofter camouflage for problems.

[shadycon]

Re-weld? Do you mean it was welded when built then welded again because of breakage or wear?

[fjruple]

Hello,
Last weekend while firing my carbine I had a major bolt failure. I'm guessing that the bolt was not fully rotated when it fired, but in any case the main lug snapped and the secondary lug took a chunk out of the receiver as shown in the attached pictures. Luckily no one was injured - the backup lug performed its job perfectly in that regard!

Problem is - the receiver is now unsafe to fire. Both the CMP and Fulton gunsmiths have stated that repairing the receiver is outside of their means, and even if it does get repaired, there is a good chance that the receiver is partially to blame for the bolt's failure. Which leaves me with a 98% perfect receiver that is not safe to fire. Amazing what 1/16" of damage can do...

I've resigned myself to this fact, and am in the process of sourcing a new receiver, but I was wondering what my options are. I do not plan to keep the receiver, so I was planning to sell it (with large text in the title being NOT FOR USE). Would these forums be a good place to start?

EDIT: Noticed that I did not state what the receiver is - it is a Winchester SN 123XXXX

Sorry to hear about your Winchester M1 Carbine. Before I would do anything about fixing your receiver. I would have the receiver checked against the original drawing to see if the receiver has been changed by stretching. Next I would get the reciever magna fluxed to see if there are any hidden cracks or breaks. (other than the left lug). With the original drawing I would send the receiver to a company that specializes in micro laser welding and have the left lug rebuilt to spec. Micro laser welding is strong and does not spread a lot of heat over a wide area like TIG or MIG welding. The problem is going to find someone to do the work. Just a thought.

--fjruple

[CrossedCannons]

What is the reason that "missing chuck" from the receiver behind the bolt's left lug needs to be repaired? The bolt's left lug is UNSUPPORTED in a "normal" carbine throughout the firing process. I'm not sure why it's even there except perhaps to provide general guidance for bolt travel when unlocked.

FWIW, at least one of my carbines has a similar "missing chunk" from that corner of the receiver as it came to me directly from the CMP. Presumeably they inspected it and I thought it was in fact "normal" at one time (my drawings aren't particularly clear in that area) but I have since been shown over on the CMP boards that it was due to breakage as it is obviously different from "new". But this carbine has fired thousands of rounds full auto in my possession without so much as a hickup. So I ceased worrying about it.

Knock on wood

[M94/14]

The Carbine was designed to have contact on both lugs of the bolt. On all 3 of my Carbines, both bolt lugs have contact with their corresponding locking shoulders in the receiver. If yours don't, I'd be trying to figure out why.

It may function OK for awhile, but with only the right lug contacting, I see a broken bolt in the future.

[CrossedCannons]

The Carbine was designed to have contact on both lugs of the bolt. On all 3 of my Carbines, both bolt lugs have contact with their corresponding locking shoulders in the receiver. If yours don't, I'd be trying to figure out why.

It helps to have original references. Your eye is probably not precise enough to measure small gaps

Drawings for both bolt (7160092) and receiver (6544004) specify that the left rear surface (of left bolt lug and left receiver notch)
shall be within 0.001" to the rear and 0.003" forward of right hand locking surfaces.

Since there is/was no "fitting" of specific bolts to specific receivers, only one of the bolt lug's rear surfaces may contact the receiver at any given time. In effect, this clearance means that, by design, only the right lug in contact with receiver supports the bolt during fire.

If that lug breaks during fire, then all bets are off and the left lug will contact the receiver in a fashion it was not designed to do.

[M94/14]

It helps to have original references. Your eye is probably not precise enough to measure small gaps

Drawings for both bolt (7160092) and receiver (6544004) specify that the left rear surface (of left bolt lug and left receiver notch)
shall be within 0.001" to the rear and 0.003" forward of right hand locking surfaces.

Since there is/was no "fitting" of specific bolts to specific receivers, only one of the bolt lug's rear surfaces may contact the receiver at any given time. In effect, this clearance means that, by design, only the right lug in contact with receiver supports the bolt during fire.

If that lug breaks during fire, then all bets are off and the left lug will contact the receiver in a fashion it was not designed to do.

Unfortunately, I, unlike you, do not have access to a set of Original Carbine drawings, so I do not know what the dimensions are, or should be.

However, my eye's are precise enough to notice distinctive wear patterns on the left bolt lug locking surface, and corresponding wear on the receiver locking shoulder. All of my Carbine's are like that.

None of my Carbines appear excessively worn, so I doubt my right bolt lugs, or the right receiver shoulders, on all three Carbines are worn down to the point where I now have contact on the receiver locking shoulder with the left bolt lug. The more believable scenario is that they were designed that way...

I will add that I find it hard to believe that the Winchester Engineers who designed the Carbine, would design a firearm with only one bolt/receiver locking surface. Surely the Ordnance community had learned their lessons with the Krag.

I can also see that were are likely to never agree on this, so as long as you're happy with yours...

[noobzor99]

What is the reason that "missing chuck" from the receiver behind the bolt's left lug needs to be repaired? The bolt's left lug is UNSUPPORTED in a "normal" carbine throughout the firing process. I'm not sure why it's even there except perhaps to provide general guidance for bolt travel when unlocked.

FWIW, at least one of my carbines has a similar "missing chunk" from that corner of the receiver as it came to me directly from the CMP. Presumeably they inspected it and I thought it was in fact "normal" at one time (my drawings aren't particularly clear in that area) but I have since been shown over on the CMP boards that it was due to breakage as it is obviously different from "new". But this carbine has fired thousands of rounds full auto in my possession without so much as a hickup. So I ceased worrying about it.

Knock on wood

Hmm. Yeah, the CMP made it clear that the receiver might be to blame for the bolt failure in this situation - and that if this is the case it will keep breaking bolts.
The other possibility is that the recoil spring is too weak and did not have the power to fully rotate the bolt, which led to a partially rotated OOB.
In any case, I am replacing the recoil spring and receiver. It really looks like the carbine fired without the bolt being fully locked either way, and that does not seem safe to me. The backup lug performed well this time, but now that it is half gone I don't want to think about what could happen if the same situation occurs...

In case anyone is interested I was using run of the mill PPU ammo - I don't think the ammo was to blame. I also did check headspace on the rifle when I got it and the bolt would not close on a field gauge.
Makes me wonder - if I had spent the $5 on a replacement recoil spring earlier...

[browningautorifle]

if I had spent the $5 on a replacement recoil spring earlier...

Don't second guess yourself...if your aunt had a couple things she'd be your uncle... What happened, happened and if you aren't hurt, then that's sometimes as good as it gets. I broke a receiver and simply parted out the carbine and carried on. Too bad to, it was a second serial number block Winchester...(parts gun)

[imarangemaster]

Re-weld? Do you mean it was welded when built then welded again because of breakage or wear?

It was a de-milled receiver that was re-welded and re-parked. They were not uncommon in the 60s and 70s.