I'm glad to see the hunting sub-forum is getting off and running.   My personal experiences with single shot hunting is very limited----to shooting nuisance raccoons and woodchucks at my old family home which my sister now owns.

However I do have a dedicated single shot rifle "in the works" and hopefully it will be ready for the next deer season. It will be based on a Ruger #3 45-70 and a modified 45-70 case.   

here in the midwest we have been gifted by Mother Nature and some state DNRs with a rapidly expanding whitetail deer population.  Many of the Upper midwest states have have long had regulations that made hunting with rifles illegal in much of if not all of the state. Basically population densities in the more settled areas precluded high power hunting rifles for safety reasons.  Indiana was a shotgun only state for many years as was the southern half of Michigan's lower peninsula.   

However the deer being deer don't know the regs and operate strictly under the biological rules and regulations.  as a result in the more settled areas where hunting pressure was less and agriculture was good the deer population is burgeoning while over hunting for antlers in the traditional rifle areas (of MI) has really lowered the "quality-hunting" in the former rifle only areas.  In addition the number of deer hunters has dropped as the generational change and the younger folk have sought other sporting interests.  the expanding deer population has resulted in a large increase in deer car collisions---including the number of human injury and fatal accidents.  there are also increased in crop reductions as a result of deer depredations.  Pressure from the powerful Insurance and farmers lobby groups has resulted in the State DNR's liberalizing bag limits legalizing general population of use of crossbows in former traditional bow-only seasons and legalizing the so called "modern-muzzle loaders" in the formerly traditional muzzle loader seasons and areas.   

Statring a few years ago OH IN and MI have also permitted the general use of "rifles" chambered in high-power (nominally) pistol cartridges. (with the .357 Magnum as the lower limit up though the 454 Casual, 460 S&W .480 Ruger and the traditional magnums)  The IN and MI regs define it as a straight walled cartridge of no less than .357 bore capacity and a max, case length of 1.87 inches.  some stated had permitted "traditional B.P rifle cartridges)

Sounds like the old .40-50SS would be perfect for hunting deer in your area! Meets all the dimensional regs and would bring down a buck with ease!

You don't need a special reamer, just short chamber the barrel and cut the rim recess on the lathe. I've done it and it works. You are basically using the front 1 7/8" of the reamer and the diameter at the back end is large enough that the part of the case just in front of the rim will chamber. You can use standard 45/70 dies to load your ammo or you can shorten the dies if needed. I didn't need to. As I've said, I've done this and it works. you don't need to spend any $$$ to do this project.

Shortened .45-70 brass is what I use in the 11.7 Danish Rolling Block. I think the length you're going for matches the Danish 11.7 pretty closely.

Way to go. My favorite type of hunting.
Lee

?Maynard, I think you may have pretty much duplicated the 45/60 WCF. A very popular round designed for the Centennial Model 1876 Winchesters, but also chambered in some Hiwalls. I think the original load was a 300 gr. bullet at about 1300 fps. Brass and dies are available correctly marked if you are fussy about that sort of thing. The reproduction 1876 rifles really brought the demand up and the prices are much lower now due to higher volume. You might have to trim a few thou off the length to make 1.870
Anyway, sounds like fun. 
Happy New Year to all!
Dennis