I've proven to my own satisfaction that all rifle barrels from at least as small as .36 calibre and larger to .69 will have a sweet spot for both 3F and 2F. In the larger calibers, 3F has lost out in the velocity game prior to 2F, meaning 2F will maintain accuracy to a higher velocity than will 3F - in calibres larger than .45, but not including .45.
Bear in mind, my criteria might be different that yours. I absolutely refuse to have to wipe the bore while I'm shooting and that goes for hunting as well. This means I will not use a combination that causes fouling to accumulate.
Thus, 2F has given me better hunting ballistics in calibers .50 and larger, whereas, both 3f and 2F are identical in speed below that calibre at 'best' accuracy. This means higher velocity, which means flatter trajectory. I did not say the powder charges are the same - they are not the same in any calibre - can't be. I will also state emphatically, neither fouls the bore with any charge used in developing the above personal stats.
Another 'fact' I've discovered, that due to it's development of producing higher and 'quicker' pressure, patches used with 3F must be more substancial than patches used with 2F - this does not to mean you can get away with panty material, just that as pressures rise, 3f puts more strain on the patch than-does 2F.
