Brad's first M74 in .50 -3 1/4 had NO leade before the lands started, which I am lead to believe was normal chambering for original rifles.
He ended up with my .50 3 1/4" witch had a good 1/2" of leade and kicked too much for me as I was shooting a 550gr. at about 1,760fps. It was not fun, hurt too much, so I sold it. I could not get it to shoot with black powder with the bullets I had at hand. The fellow who bought it, fired a couple, cut the butt off and put on on a recoil pad, didn't like that, so sold it to Brad. LOL
As I understand it, Shiloh is the one who 'developed' the long throat calling it a paper patched bullet throat. The trouble with that, is the free-bore or long leade (which ever you want to call it - is OK) hinders chambering a ctg. due to blackpowder fouling in that leade or freebore unless the rifle is cleaned between shots.
According to Paul Mathews, original ammo had tapered bullets with only the base being close to groove diameter(after patching), and patched to fit the bore, allowed long bullets to be used in the buffalo rounds - in any so-chambered rifle, not matter the groove diameter. Due to being pure lead or nearly so, they obturated to fill the grooves.
After reading "The Paper Jacket", Taylor and I bored a Lyman 4-cavity .44 mag. mould to cast 460 and 580gr. PP bullets of correct size (.438") such that after patching the pure lead bullets, they just scrubbed the lands in my .45 3 1/4"Rolling Block that did not have a long leade. We cut another mould to cast a 400gr. PP bullet, that did the same and shot well in his Shiloh Sharps .45 3 1/4 that had only .015" deep rifling - yes - 1 1/2 thou. deep. Cast in pure lead, these bullets shot 1 1/2" in Taylor's M74 Sharps and 1.2"@ 100 meters for the 580's in my Hoch Barrel (14 pound rifle)
As Paul stated, using these undersized bullets and lube cookie'd loads, we were able to shoot 2, 5 shot groups, then push a DRY patch through the barrel and ALL the fouling would push out- gone. We adjusted the grease cookie to leave a thin star on the muzzle's crown.
Seems to me, Taylor's .45 3 1/4" barrel had a long leade (we could check it). The 400gr. MASKING TAPED (1 wrap) pure lead bullet shot very well in his rifle, not-withstanding the so-called paper patch throat. Perhaps that is the key to getting the long throated Shiloh rifles shooting? My Hoch barrel did not have a long leade or throat. Pushing a patched bullet through the bore left a perfect bullet with 6 lines marked on the patch from the lands - just as Frank Meyer said should happen, so many years ago.