I've though about that for one of my MHs, but I'd be too concerned about the metallurgy of a 145 year old receiver to trust it with modern shells loaded with fast-burning smokeless propellant. Not a lot of cross-sectional surface area on the receiver sides to hold the block from moving toward my face, and lots of environmental effects could have happened over the years to embrittle the early steel . I'd have to stick with hand loading BP shotgun shells.I’ve got another barrel for a shot gun/ Martini experiment. 24 gauge.
This rifle is bad ass cool , a SG for shooting turkeys would be pretty a nifty venture too I think.
If you ever run across a MH action and feel like making some specialty ammo ,it could be a pretty easy bit.
I’ll shoot Red Dot 180 ers in this one or just stuff them full of black powder maybe.
So for now I'm still having fun playing with paper patched 577/450 BP rifle loads. Plus it's fun to go to the range and listen to every else's pop-pop-pops and then I go KA-BOOM.