I note the practice of loading the "neck" (sprue) down in the patch guns.
Lon
Lon - I think you are confused as the the 2-piece slug used. The softer base tit (not sprue) goes up inside the hole in the base of upper, harder part of the bullet. The 2 pieces are then swaged together in a hammer swage to become a 2 alloy, 1 piece bullet. The lower, ofter part obturates slightly with the paper patch to fill the grooves and maintain a gas seal, while the upper, harder part rides on the lands. (that is, unless I missed the pictures you are referring to.
Since we know today (since about 1900) that the base of the bullet is the most important guiding part of the bullet and must be perfect. Loading a sprue down would destroy the ball's (or bullet's) perfect base and give uneven gas escape at the muzzle, thus an 'off shot'. We can properly centre the sprue at the top, but not at the bottom. Even thus, centering the sprue at the top isn't as necessary for hunting accuracy, but when trying to get every last vestige of accuracy from a gun, we must do everything as perfectly as possible.
My bro is one who doesn't seem to care where the sprue is positioned, sideways, up or down. I've observed him loading like that many times and indeed, he claims it makes no difference. That he shoots as well as he does, offhand, is amazing as we know that any enlargement of normal group size due to irregularities in loading shows up in any position. This induced error in accuracy increases almost exponentially when shooting offhand (for most of us mortals), just the opposite to what many believe. Now, take this man, Taylor, who is almost infallible in his offhand shooting, and set him at a bench, and his bench groups almost perfectly mirror his offhand group size. Glad I am, that he is careless in loading, for if he took the time to load 'perfectly' he'd be virtually unbeatable - in any position.