This rifle is a little weird in that I get AI velocities with hand loading data for the factory cartridge. These loads are almost always in the lower end of the range shown in the loading manuals. My gunsmith and I have never been able to figure out why this happens, but it does.
I had a .220 Swift that gave crazy velocities. Also blew primers right left and sideways with book starting loads. Finally chronographed some. Starting loads were about 200 fps faster than the max loads were supposed to be.
I never expected IMR 4831 to be the solution for a Swift but it worked. I managed to get to the max load of 44 grains under a 55 grain ballistic tip. Something in the quarter inch range at 200 yards ... I was knocking consecutive push pins through the target at that distance.
My best guess is that barrel was way, way, tight.
