Ray,
Is your pot a No.10 dutch oven with legs? That's what the red book says for catalog No.1300. The cover should be a flanged cover to hold coals on the top but perhaps someone has substituted a standard Wagner (are the basting rings notched?) or Griswold cover (smooth basting rings) or another type of cover.
Troy Hockensmith may be able to help you more.
Whoops, I now know what you have-I was thinking it might be a Wagner piece but you say oval roaster so I remembered what you have. Is the cover catalog 1301 maybe? In any case it is not a Wagner or Griswold piece and I don't think anyone really knows who made it. The cover resembles a Griswold cover in the details but it isn't. Sorry I can't tell you more but the piece, while often seen, is a mystery to me as to where it came from.
Steve