Bob (pod) I don't believe a hammer for end will work, the reason is on a hammerless gun you have cocking rods, and they hit on a cocking plate to recock your internal hammers. The area in the for end should be milled out to accept the cocking rods. Naturally hammer guns do not have this.

Early Syracuse "elsies" both hammer and hammerless looked very close in comparison, but they both used a joint check to extract the shells.

David