A long cone does not actually ease loading - seemingly increasing drag and the pressure requited to load, as we found out with the first of LB's .40's. He'd run out of balls, so I gave him some of the ones I was using at the time in my .398" bore, Goodioen barrel.
He complained that he was having a lot of difficulty loading the bore size ball in his coned muzzle, yet in my .002" tighter crowned muzzle, they loaded easily. To understand this seeming phenomenon, one must learn about drawing metal and the angles needed for that. When I tested the .400's in his .40- he was correct. In my .398 (.40)- they loaded into the muzzle & down the bore quite easily in comparrison.
The crown we've been preaching for many years (since the 1970's) works like a charm. I learned this from reading up on Corbin bullet swaging, and drawing process where they discussed the necessary angles.
The coned muzzle might allow easier loading of what we think of as already too loose a combination. With the tighter combos, coning, as least as in LB's rifle, made for more difficult loading of a really tight combination.
