Are you going to send it back? It's a casting inclusion usually found internally when magnafluxed or X-ray-ed. I've only encountered it once in a single shot 45 cal barrel of 4140 alloy. These percussion gun frames are usually made of 8620 alloy.
No, no need to. It will work just perfect and if it's a conversion, will handle +p loads just fine.
Yup
Yes, they are investment cast (lost wax method in ceramic molds) and then milled/shape'er cut to spec.
No, the pock mark is indicative of a minor casting flaw that was milled into and this one has what looks like a small crack emanating from it.
It could have just been left over slag, or mill filings filling it but was commenting on what the original post said of it being filled and found when picking at the pock.
Well they are largely milled/shaped from solid stock but this is an investment casting rather than the original forged billet.
