I am in the process of collecting parts for a USC/UMP conversion and I purchased a barrel from a online dealer that I have heard only good things about. I was happy I finally found a factory barrel. It has a polygonal bore, but since I made the purchase I've started noticing all the factory barrels that I've seen pics of have an HK logo engraved on them. Mine does not. Then today I found on gun broker a USC barrel that was converted to look like a UMP barrel and realized mine looks very similar to it. I really wanted this conversion to be as close to a factory UMP as possible. Is there any other markings taht could confirm or were there years that they didn't engrave the UMP barrel with "HK"? or did I get ripped off? Thank you for your responses.