The Hepburn has its firing pin at a steep angle. This requires precise bushing and fitting to prevent the firing pin being stuck in the primer. That may be the biggest impediment to greater than black powder pressures. Otherwise, the action is strong.

Believe it or not, my varmint shooting partner from the early 80's had a Hepburn built up in the .22/30-30 Ackley Improved. The action held this cartridge fine, but he experienced problems with firing pin hangup early in the rifle's career. A little tweaking did correct this problem. Personally, I would not be so bold with a Hepburn unless the breech block had a major re-build on the lines of a Neidner-Mann treatment. I don't know if this is possible with the Hepburn block.

As said, stocking this action presents very limited possibilities. An all-out schuetzen style will be your best choice if you want to be true to the action's history. I once saw a beautiful schuetzen rendition of a Hepburn in fabulous flame colored fiddleback maple done by Hal Hartley. Something like that in a traditional caliber from 32-40 to 45-70 would be a lot of fun.

The only Hepburn in my past ownership was chambered in .22K Hornet. It retained its original wood from Remington. For some reason I could never get acceptable accuracy from it (the Hornet and K Hornet are notoriously difficult). I let it go for other horizons.

My very favorite vintage American action is the 1878 Sharps Borchardt. My next favorite is the 1885 Winchester High Wall. Sadly, all are gone to my demanding double rifle habit.

Curl