I have a Win. M43 in .218 B and it shoots very well. Groups under 1" at 1 hundred yards.
My load is 12 gr. Lil' Gun Win. Brass, CCI SPM primers with the40 gr. Speer bullet which will feed from the magazine or the 40 gr. VMax or Nosler Varmageddon loaded single shot. Velocity is 3070 FPS. Can go higher brass doesn't hold up as well. Neck size when possible.
A GREAT squirrel load is 4.3 gr. Unique with either the 40 gr. Speer or .45 gr. Speer Flat nose. Groups under 1/2 inch at 50 yds. Vel. 1600+ FPS.
Lighten up the trigger by unscrewing the trigger spring screw a little and fool with the stock screw tension.
Good Luck!
Hip
