Help: Load problem

[BCDeerWild]

I am having a problem getting a load to work in my fireformed brass. My fireforming load is 43gr RL22 and a berger 105 seated to fit my magazine. It shoots .25 MOA out to 800 yards. I kneck sized the brass with a redding knecksizing die, kept my seating depth the same and I am getting 8 to 10 inch groups at 500 yards. My velocity spread is over 200fps average. Goes from 3200 to 3400 fps. The fireform loads had a spread of 6fps. Every thing shoots right on at 100 yards. My ladder test looked like a benchrest group.
Any suggestions would be appreciated.
Thanks