Actually, the taper of the .30SC is so small as to be unnoticeable.
The real problem is that there is no rim to stop the case from falling into the chamber past the point where it could be struck by the firing pin.
In other words, the .30SC headspaces on the case mouth, the .327 headspaces on the case rim.
My reloaded .30SC are sized in the same sizer die as the .327. Ditto, .32acp, .32s&w, .32S&WL, .32H&R.
Top velocities are actually a tad lower than .32H&R as there is somewhat less case capacity.
For instance, the .32H&R does quite well with #2400, Lil'Gun, and H110. The .30SC won't hold enough of either to generate enough velocity/recoil energy to cycle the action with a 100gr bullet. On the other hand, HP38 exceeds working pressures before sufficient velocity is obtained.
Best powders I've tried so far are AAC#7, LongShot, and ACC#5, in that order. #7 comes within 35-50fps of matching Federal 100gr HST.
I doubt the .30SC will get much traction. I'm still sitting on my S&W Super 9, with a .356TSW barrel. Last one I saw on GunBroker went for more than $4000.00. Besides, my .30SC (Sheild EZ) is a tack driver... and is a treat to shoot.
I recently sold my Ruger Sec-6. I bought it for $125.00 off a vendor table at the 2000 NPSC. I got $600 for it. Seems last century "trash" is now desirable "unobtanium"...
And, BTW, I've been around a while. Just had to re-register as my old email address is no longer usable.