"I had an IJ Carbine in the early-mid '80s. I had to send it back to the factory because the bolt was too soft, and the locking lugs began to peen. It's my understanding that many IJ Carbines had soft parts."And my reply:
This is a quote from your 17 Sept 2004 post on "THR". I am emailing you because I need some advice.
I bought two former Missouri police dept Iver Johnson Enforcer pistols. I haven't put too many rounds through them, but on one, the bolt cracked. Upon further inspection, I saw some of the peening you described. I could buy a replacement IJ carbine bolt from Numrich, but was their rifle bolt different from their pistol bolt? I'd be better off with a GI or M-1 GI type M-1 carbine bolt, of course (no soft metal in the GI bolts) but upon inspection, the IJ design for my Enforcer was different. Simpler, easier to clean, but different than the GI design.
How did you resolve your soft bolt problem?
I had purchased an extended warranty from the store where I bought my IJ Carbine, so when I noticed the locking lugs starting to peen, I took it back to the store, who shipped it back to IJ. I got it back with a new bolt. Unfortunately, IJ went out of business awhile ago.
What I'd do in your case is to replace the bolt with a USGI M1 or M2 Carbine bolt. I'd prefer the later round style over the earlier flat bolts. The round bolts are stronger, and have more mass. I would not buy an IJ bolt from Numrich, since there's a good chance you'd end up with the cracked bolt problem again.
No matter which bolt you get, I suggest having a gunsmith familiar with M1 Carbines check the headspace. I wouldn't count on it being a drop-in part.
Of the M1 Carbine clones made for the US civilian market after World War II, the Plainfields and Iver Johnson (after they bought Plainfield) were generally the best. Quality deteriorated towards the end of production in 80s, however, as demonstrated with my IJ Carbine, and the two Enforcers mentioned above.
Universal Carbines were generally not too good, and in fact are not true clones. While the Plainfields and IJs will take USGI parts, Universals won't.
More recently IAI made some Carbines down in Texas, but has since gone out of business. From what I've read, they had a lot of problems. The only current manufacturer of M1 Carbines is Auto Ordnance, which is owned by Kahr. I've heard mixed reports about the Kahrbines (pardon the pun) but IMO, they'd be worth a shot (groan) if you are in the market for an M1. I find it neat that the AO Carbines are being produced in WW2 format, i.e., without the bayonet lug and with the "L"-type flip rear sight.
I sure like my original Underwood M1, though. :-)