The long-time old standard target load for .38 wadcutters is 2.7-3.0 grains of Bullseye (or 700-X). For 158 grain RN or SWC bullets, you can go up to 3.5 grains. You can go a little higher, say 4.0 grains but no need to. The Colt Army Special is a little beefier than the S&W K-frame and will handle higher pressures with relative ease.