With the 222Magnum being nearly identical to the 223 I used 223 data with IMR 4166 in a 222 Magnum in a Rem 40-X. With the 50 gr Ballistic Tips, Nosler brass and CCI 400, I went from 24.0 to 26.0 in 1/2 grain increment. Velocity increases were linear and with the 28” barrel I got 2965 fps at 24.0 grs and up to 3215 at 26.0 grs. Accuracy was very good with five, 5 shot groups of 0.3, 0.4, 0.5, 0.4, 0.25 inches. So nice accuracy, just a little slow.
With CFE 223 (again in the 222 Mag and the 40-X) and same cases, bullet, etc and 1/2 gr increments, 27.0 grs gave 3115 fps, 28.5 grs gave 3345 fps. Four, 5 shot groups were 0.55, 0.5, 0.75, 0.4 inches so better velocities and close to the accuracy with IMR 4166.
