So, in an effort to make sure I should really be irked at myself, I may have a welded receiver on a M1, but thanks to some other posts elsewhere, I'm just flat confused. Specifics are:
Sn 530xxxxx
Drawing F 65828291, with an A55C.
I read that that draw and heat lot are associated with IHC and the F number showed up only on Springfields after 545xxxxx (I think); but now I see posts that it actually showed up on Springfields as early as 533xxxxx, and I haven't been able to snatch a copy of Duff yet. If it is indeed welded, that guy did a great job. Nothing noticable under the loops, passes the dental pick test, and the park isn't in the greatest shape anyway (although I have cleaned that gunk from the latch recess).