You will probably notice that BP gives more of a push rather than a kick when you shoot. Some guns are made with a rifling rate of twist designed to shoot roundballs. Roundballs generally need patches. Guns with a faster rate of twist designed to shoot Conical Bullet or Sabots won t use patches with those projectiles. Make sure that you have removed all traces of oil and grease from the inside of the barrel , even the breech face.
Alcohol works well.
Place your ramrod in the barrel and put a mark on the ramrod that is even with the end of the barrel. This can be used in the future as a reference to check that the gun is completely unloaded and has no obstruction in the bore simply by placing the ramrod in the barrel and checking where the mark is. Remove the nipple from your rifle and ensure that no grease or oil is present in the snail or drum. Ensure that the nipple hole is clear. Clean these areas with alcohol.