Breech plug,
Several years ago i think it was the late 80's I had a white mountain carbine. I played around with it quite a bit and developed a load of 53 gr of Pyrodex RS and a 385 gr buffalo bullet and CCI primers and got fairly go accuracy. I actually killed a big doe with that load around 45 yards. I don't think that I would go lower in powder. cayugad has said in a couple of posts about using a heavy bullet and I think he said he used 60 gr of powder. If was to go back to a low powder charge it would be with a heavy bullet. I would think a 300 gr SST and say 60 gr of Pyrodex would do the job as long as you have accuracy. I hope this helps with your delimia.