I’ve heard all my Muzzleloading life to always load a round ball sprue up. “I” have loaded them both up and down and can see no difference in accuracy...at least not at “my” normal hunting distances.(<75 yds) In my smooth bore “I” load the sprue down .... “my” way of thinking is when the ball leaves the barrel at least 3/4 of the ball is still round and pointed down range. Right or Wrong .... “I” don’t know, just “My” way of thinking. As Mr. Dutch pointed out in the other thread , we deform the ball when loading it into the rifle anyway. Unless your rifle can be thumb started and you have a fantastic lube that allows you too gently push the ball down the bore and seat it on the powder charge. Which is possible, but in most rifles “I” have found that’s not the case, especially after a few shots fired even when swabbing . What I mean by swabbing is a “spit patch” up and down the bore using both sides prior too reloading. Not a complete cleaning. Loading sprue up using a short starter would help flatten the sprue area bring it back closer too it’s original shape .... maybe this is the reason for sprue up . As far as a “void” behind the sprue location, “I” would think if your temp is right on your lead and you make one continuous pour , chances of a “void” is almost eliminated....??? IDK. But does it really make a difference in accuracy if there “was” a “void” , if it was loaded towards the front of the bore or the rear??? I am NOT a world class shooter , but can usually come fairly close too what I’m aiming at. Others mileage may vary.