I assume these were sand cast, correct? The ones I see are usually nice and straight, this one looks to be warped. Although the ID appears to be straight, I'm wondering if the outer profile is twisted and warped but the machined taper is perfectly straight? I don't have a No 7 spiral taper reamer to check it but . This came off of a 1980 NM rifle with an honest 250 rounds thru it. Do you think this is aftermarket, or is it original SA piece? Is there a way to tell? Thank you in advance.