Hard? None of my rifles is hard to load, but all of them require the use of a short starter.
Tales (writings) of rifle matches and the accuracy achieved, stacked balls at 50yards for instance during the 1800's, show that they could not possibly have been using thumb started loads - in my opinion. The reported accuracy achieved, rivals or exceeds that of most of us, today who use short starters and over-sized loads. Tales are tales, however. On the other hand, some of the 'records' are/were re-writes of events at that time, however and are not merely memories blown out of proportion due to the time between the act and that of reporting. A number of the re-prints from letters or other documentation of events that happened at the various towns or forts. Many of these are included in the books "Firearms of the American West" - these are very good historic reading- well documented as well- one massive undertaking - if you are interested in that sort of thing, get the books! However, it's much easier to make a statement "this or that didn't happen" and then demand proof it did, rather than to actually put forth some effort to investigate and find out what actually did happen. If you want to know - do the research.
As to coning, one of the lads here had a coned muzzle on his .40 rifle. He had difficulty loading the balls and patches I found easy to load in my own rifle, which had a radiused crown, not a cone. The cone seemed to make loading difficult due to the "long, high drag bearing surface of the tapered bore, whereas the appropriate drawing angle of the radiused crown (researched from Corbin) made loading easy. Thus, a single light blow to the starter, fitted the oversized ball into the grooves along with it's .020" patch. This then shoved down the bore as it was already groove size and loaded easily. That load will stack them from my rifle, to the point of a lump of lead for 5 shots, but not one on top of the other, as was reportedly done, "way back then". Was it done? More than one occurrence of this sort of accuracy at matches, seems to bear this out. This sort of thing actually increases the possibility that starters were used- by some - but perhaps only those interested in the accuracy they allowed to be achieved. Sere the commonly used? There was likely not a reason for the improved accuracy they provided - however there were "Shooting Clubs' in the East and West, who were interested in accuracy - the rifles with them in pictures along with the sights on the rifles, show the members knew what they were doing. Using short starters and tighter than normal loads - likely. Through the 1800's Remington made and sold barrels to rifle makers. These were already turned at the muzzles for a ball or bullet starter - as shown both in Ned Robert's book as well as the books I cited above.
When speed was of the essence "way back then", it is documented that patches were not used and naked balls were - the same happened when running buffalo - speed and ease of loading was necessary, thus naked balls were held in the mouth, spit into the bore after powder was poured straight from the horn, capped or pan primed (before or after loading(?), lowered and fired into the buffalo - all at a gallop - what fun! Dang - dropped my starter- HA! - none needed for that type of shooting, but - guns exploded when used that way if the ball left the charge before ignition happened. I suspect lots of balls were swallowed, as well. No wonder the M1860 Army and Dragoons were preferred for 'running buffalo'- the Colts held 6 buffalo in every cylinder.
You guys really should get those books. Great reading and full of historical facts.