I know Lefever built a few double rifles in his career, but I've never even seen pics or read what chamberings he used, so I won't stick my neck out and say with certainty that he didn't build this. I would bet those colors were the result of a torch artist, but he might have fooled us if he used a bigger tip and didn't get so carried away. Looks like a steel leopard. I can't see any telltale lines indicating sleeving. Could be original tubes with liners, but the rib, as noted above, is specifically made to transition into the rear sight. The engraved wording from the short rib extending into the long rib looks right, but a skilled engraver can do wonders. Who knows without a much closer examination? Maybe ED1 will weigh in and tell us how those torch colors actually improve the metallurgy of the action and make it safe for 40,000 LUP.