I just got an Iver Johnson M1 Enforcer that is jamming. I have narrowed the problem to a loose extractor. I want to replace the entire bolt anyway (it is badly pitted). I have been calling around for a replacement, to be told many different things. Some say the Iver Johnson M1 used a completely different spec bolt than GI carbines, others say the Iver Johnson is the same as GI, but Universal's were different. Any help before I learn the answer through wasted money?

I’m certainly not disagreeing with Troy.  However, Iver Johnson bought out both the Plainfield Machine Company (standard M-1 Carbine design) and Universal (non-standard design).  

I’d think there MIGHT be M-1 Carbines marked Iver Johnson with either design, though I’m just guessing.  I can’t see them tossing all the Universal parts.  This might also explain why you're getting conflicting answers.

Universal was the original maker of the Enforcer.  Admittedly, the standard design could also easily be modified to the “Enforcer” configuration.

The Universal design is easy to identify since it used two recoil (or operating handle) springs instead of the one spring used in the standard design.  Typically, at least, it also used a cheap looking, stamped operating handle.

Gentlemen, I thank you.