Is the engraving signed? That might help answer your question. Go over it with the best glass you have & see what you can find. I'm not even a remote knower of what they did or didn't do to 21's, but have owned several and enjoyed them and that is the more important part, IMHO. Just take satisfaction from using it and don't get too caught up in the originality thing unless you bought it as being factory, in which case the seller might have some responsibility if it was represented that way, otherwise who cares really? If you are contemplating selling, I can see where it may matter. If the engraving is well executed and you like it, whats more to say? If it has the '6' & it matches other other known lettered '6''s then you have a good argument it is factory, in my unexpert opinion. If it does not match, then that's a dif horse.
Lots of guns have been 'up-graded' some better than others and some better than the originals. I suggest you judge your own gun by itself and let it stand on its own merits. It sounds quite nice.
What are the bbl lengths and chokes, if you don't mind my asking?
