the itm/oow is about .060" too long, and require a careful pre-fitup to get the mag engagement height correct.

the rec. is also too tall by about .025"-.030". this requires thinning the selector stop .020" prior to riveting in place in some cases, in order to get the bolt to reliably strip rounds from the magazine.

the selector hole is a non-issue.

the heat treatment is only around the hammer and trigger pivot pin holes as well as the ejector tab. probably good enough to last 50k rounds if used as a machinegun, but still much softer than the commie receivers.

several outfits are offering to fully heat treat the itm/oow receiver (a worthwhile investment in my opinion).