Fire Forming 240 Banshee

or maybe your spray lube does the trick, lightly lube the inside neck. If you overdo it stick powder can bridge. I simply FL size the case, the expander ball gently expands it to .241" or so. Load up and seat a .243" bullet of your choice. Upon firing it will blow out a nice full improved .240 Banshee case. When loading them only push back the shoulder of the case enough to reliably chamber. No need to overwork the brass. Chamfer the cases prior to seating the bullet, no need to mouth expand. It's a rifle round anyway. No need for a crimp at all.

Are you loading for a revolver or single shot? Do you have Mr. Taffin's book "Smallbores" where Gary and I recounted much of the process in depth?

It works best for the K-Hornet but usually works with new brass too.
Take regular handgun powder, like unique or other flake type pistol powder. Fill the brass case up to where the shoulder starts and stop there. Pour the powder into your powder pan and see how much it takes to get it to the shoulder. Keep that in mind and if it works for you then you will know how much powder to put in the rest of your batch.Fill a couple of cases to the shoulder and take a half square of toilet tissue. Roll it into a ball and put it down in the case. Tamp it down tight against the powder. Make it tight but don't hit it as powder will fire. Then take each case by itself with the tissue as tight as you can against the powder in the case. Then take the cases outside, point it up and fire it. It normally will form the case on one try. It should have the Banshee sharp shoulder and short neck. I have had to do this twice from time to time but in most cases the shoulder forms real well the first try. This way you on't waste a bullet and only a small amount of powder.
Some people like the water pressure way of forming the shoulder. They fill the Hornet primed case up nearly to the mouth of the case with water. You take a decapping rod or any rod that is real close to the size of the neck of the case. Getting the rod as close to the diameter of the case neck works best. Then put the rod into the case and if the rod is real close to the size of the neck take a hammer and hit the rod a good whack. The pressure of the water in the case will usually form the shoulder. I have never used this way of forming the shoulder but have had several friends tell me that is the way they do the case forming without wasting the powder and a bullet.
Good luck
GNR.