In my two Hellcat Pro's, (3.7" bbls), with 147 gr. Extreme Plated RN, mixed brass, WSP or FC200 primer,1.145 OAL, Lee FC:
3.6 gr titegroup averages 958 fps, 26ES, 10SD
4.3gr CFE Pistol averages 966 fps, 12 ES, 4SD
Can not really see any differences; both seem to burn cleanly; target accuracy...