I had been neck sizing my fire formed brass to get enough tension to keep the bullet from falling in or out of the case. Accuracy with BP substitutes last season was generally not to bad but in nearly every five shot group there is at least one really wild flier.
During the winter I built a 20 gauge Paradox gun. The barrel was shortened to 19", threaded on the OD, and then I put on a 6" section of an old, badly pitted, Snider barrel. At 50 yards it will shoot a 6" group with .600" dia round balls and NO fliers in 40 rounds. This got me thinking "why won't my Snider do the same thing?"
Today I loaded a batch of Snider rounds using the same components as the 20 gauge. A charge of powder, a Winchester 20 AA wad with the petals cut off, a felt wad, and the bullet seated in the fire formed case with just enough of a crimp to keep it from falling out. The other thing that I have changed is the primer. Instead of a large pistol primer (Magtec brass) I'm using a large rifle primer. I have the idea that when that big hammer falls it may be destroying the thin skinned pistol primer and causing inconsistent detonations.
Will test them out at some point in the next week.