Abilene 

Ah So Deska (Japanese for "No S&%T GI).  If I might, I would suggest checking with VTI, or EMF or Cimarron for a new Main Spring.  Specifically, PIETTA has a new "lighter" Main Spring in their GW II guns.  Very smooth, doesn't stack, and is not overly "light."  The new Springs came in my new El Malo.  I really like 'em.

Little Dalton,

If you are recreating the original, why not search and wait for an original Winchester bullet mold off of Ebay.  Since you are willing to spend 100+ for an Accurate, just get the original one in decent shape.

Then after finding that or before, just buy a Winchester 1882 -- 32WCF plier reloading tool and the BP you stated using and recreate the cartridge, all the way.

Starline brass and the right amount of powder will work up a good cartridge.

Just a thought.

At this point, I attribute the misfires (I think there were two out of 30 rounds in the match) to an EXTREMELY hour-glassed mainspring. 

I know you guys already know this, but Hi-Tec coatings do absolutely nothing for Black Powder shooters.  Shooting BP you gotta have enough BP compatible lube.  Hi-Tec is acceptable though, iff your shooting APP.

I'll try to give you more about the Missouri Bullet Co.s Hi-tech coated.

You can see the Red Hi Tech coated on the right in the photo above size to .313" dia.

Here is the Marlin
Dads Smith & Wesson Hand Ejector
and my Colt