Harry's post is vitally important, folks. Note - 120 shots in one day no wiping therefore no buildup of fouling - that means the last shot of the day loaded exactly the same as the first - easy. Note the patch thickness and ball size. Yes, lube is important, but more volume than exact nature or composition as straight water or spit has the same effect. In my guns, the .018" measured by a mic, is perfectly capable of heavy loads of 2F as well. For heavy loads of 3f, I use heavier (thicker) patching.
Those who can feel different fouling from 2F to 3F, either have rough, slightly pitted barrels (perhaps from Pyrodex) that are holding fouling OR they are using too thin a patch, OR too small a ball for their barrel. When I measure the store bought patches, I find the sizes marked are .003" to .005" thinner than what my 4 different measuring tools tell me the patches measure. I use 3 different sets of calipers and a mic.
A ball and patch fit that is allowing fouling to accumulate, is weak fit that can easily be remedied. This 'weak' fit, which allows successive shot's fouling to accumulate, makes successive loading difficult. An almost good enough fit will allow up to 10 shots or so, then require a wiping. Sometimes this type of load merely needs more lube - ie: wetter patch - but generally needs a thicker patch as well.
Except for the .32 squirrel rifle, my rifles can bounce back and forth between 3f and 2F with no discenable difference in fouling, even though they all require at least 10gr. more 2f to get the same accuracy. By no discernable difference, I mean you cannot tell the difference in powders as they both load identically, shot after shot, as the first shot loaded in the clean barrel.
It is possible a lube that remains to build up in the bore, as I'm told some salve-type geases do, ie: bore butter, that the buildup in the bore might be giving problems. To me, that is a moot point of contention (or acceptance) as those lubes are not suitable black powder lubes at all imho - or they would not build up in the bore, they'd remain wet to soften the fouling, not build up in the grooves as an inert substance.
note - in this case - inert - having only a limited ability to react chemically ---or ---- inactive or lifeless
Hoppe's 9 Pluss has been a good lube for shooting since my first trial with it in the 70's. Yes, it has changed somewhat, not as thick and no longer creamy whitish, but it still works well. In Taylor's 5 day test during the winter, into the house every day, then back outside into freezing weather the next, there was NO rusting and no fouling of the powder.
This is is not to say that it would not have rusted the 6th day - but for 5 - it was OK - here in PG ie: low humidity - but frosted and went dripping wet each time it went into the house.
