Hello, thank you for the replies.
No, I don't think the barrel is stainless steel, I believe it is a chrome-moly that has been nitrited "melonited." The barrel itself is black and looks just like another chrome-moly nitrided barrel I own. The difference between this particular barrel and the other ones I own or have seen is that the barrel extension is silver in appearance and I was wondering what it is made of. Also, is this something normal for a manufacture to do, or would this be something that was done by mistake? By mistake I mean is it a stainless steel extension on a chrome-moly barrel, or a chrome-moly extension that missed a nitride treatment, or is it raw chrome-moly.......? I don't think it will affect function at all. For all I know these mentioned scenarios are all normal barrels and I am just use to all the parts having a nitrided treatment and look.
As far as more markings on the barrel it is stamped 5,56 Nato 1/7.
I am just curious to know what material I might have here so I can treat it properly. Also, I have tried to post a picture I took of the barrel extension, a picture is worth a thousand words, but I am unable to currently.