I purchased an ArmsCo over under shotgun to SBS.  The problem is that the markings on the gun are incomplete, i.e. there is no model number engraved anywhere on the gun and of course item 4d on the Form 1 is "Model as marked on firearm".  Should I leave that block blank, do I take photos of the gun as well as the end plate of the box to show model.

BTW I tried doing a eForm 1 online and couldn't get past the manufacturer section.

WTF Over!

Have you tried calling the manufacture? They should be able to tell you were the markings are. Maybe they are under the hand guard?

Armsco or Armscor ?

Armsco was a US importer of Turkish Huglu shotguns. Huglu has had more importers than I can count.
Armscor is a firearm manufacturer in the Philippines, Rock Island Armory is their US importer/subsidiary.

It's an ArmsCo.  I've talked to a couple of guys and the consensus is to take pictures of all of the markings on the gun as well as the end flap of the box it came in and include them with the Form 1 application.