I suggest a bit different view point,there is a minimum thats true but the real key for unknown situation that might developeis consistant tight grouping, if you can placethe shot exactly where you need it to be, then you will get the best results. Now in my view there is a systematic way of getting to that point and you start by shooting the load that the gun will shoot best. A rifled barrel vibrats or whips if you prefer in a circle because of the twist applied to it when it spins the bullet, it has been shown that if the bullet exits the barrel at the exact point that it was at rest [ie the end of the circle] that is the point at which it will shoot the tightest group and be most consistant. The best way to find this point is to find the sabot that fits right [I believe that there are 7 different ones] but only one will normally shoot under an inch and useing loose powder start at 70 or 80 gr and work up until you know what the best group your gun can achive with that bullet and that powder keep good records and throw out any thing that might be human error. Finding the right sabot and I do a lot of this at home you can take out the breach plug and push them through an inline if they are not tight they wont shoot good if they are so tight you want to pound on them they probly wont shoot good.Study the powders and there advantages and disadvantages [they all have them, the disadvantage of the best one is price] do the same for bullets it will narrow things down to where they are practical. People who think that getting amuzzle loader to shoot really well is easy are usually mistaken. Lee