It should have stamped either Ilion or Gardner in the main stampings on the frame,
The #'s they put on the lug are just with a vibrating scriber, usually the last 3 digits of the serial # as an identifier as to that barrel being fitted at the factory to that frame. Like this;
Having no # scribed on the lug could be that the factory guy just didn't put it on.,(?) Better no # on the lug than one that doesn't match the frame. A # that doesn't match the frame could mean that someone else besides the factory fitted the barrel, not a big deal really as long as you have a good fit. As you can see in the faq's and reading here, many members fit their own barrels and do a fine job of it, sometimes better than the factory,
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