Increasing the powder charge will make the round balls cross even more. You need to reduce the powder charge to eliminate the crossing shots. Personally, since 100 grains is a fairly light load for that caliber, I would try a different brand of powder, or try some Fg before I reduced the charge. You will have to vary your powder charge more than 5 grains to notice any change in regulation, I would try 10-20 grain increments.

Greg