I have used Goex 4f in my pocket model (31 cal.) and in a couple 36 cal. guns as well. No issues in operation, not much difference in fouling but seemed slightly less than Goex 3f. Would like to chronograph the loads some time as they seemed to be a bit snappier with more effect on my swinging plate targets. Using conicals and 18 grs in the 36 caliber guns, round ball and 15 grs in the 31. I was duplicating the 3f loads I normally used in these guns and they worked fine.
This subject always seems to start a real mud slinging fest with some posters. I decided to try it after reading up on the early combustible cartridges and what writers of the time classed as "pistol powder". I have also broken down examples of early metallic cartridges (didn't have any combustibles in my collection but have talked with people who did examine such rounds) loaded with black powder and examined the powder used in them for comparison. Handgun rounds clearly were using very fine grades of powder, much closer to 4f than 3f. Some of the smaller caliber rounds were loaded with powder that was even finer than modern 4f. I have no problem with using 4f in a revolver myself but many people seem to go nuts on the subject. In the end it comes down to what you are comfortable with and your willingness to experiment