O.k., I only have one suggestion for you on this...
Remember that the Sharps Rifle/s were based off an 1850's design originally intended for BP "Paper" (o.k., maybe Linen) Cartridges!
So do this (I have and I think it's most revealing)...
L@@K at that large action, that massive Breechblock. Looks pretty good, pretty STRONG, eh?
Now DROP the big Breechblock OUT of your action and view the rifle from on top, looking down (or from the bottom looking up).
Notice those SKINNY sidewalls!
Do you still have that "warm all over" feeling?
Hehe, if you're like me, you realize what you're looking at was originally made for ~20,000 psi pressures and that's IT!
(I'm not saying I have ever tested nor have I seen information on the true strength of these actions)
I'm just pointing out what I SEE when I look at that action, stripped naked.
Break out your "Hot" Smokeless...I'm stickin w/my Blackpowder.