there are Many shades of interests in most things in life and trad muzzleloaders are no exception.
there are more than a few reasons for an interest in this sport, and that interest typically dictates where and how one will start. some jump right in - lock, stock and barrel - whilst others dip a toe here and there. it's all good, one way or t'other.
the principle reason for starting immediately with real black powder is that it is the powder that was meant for these 19th and earlier century gun designs, is an explosive and yet typically generates much less pressure than bp subs and smokeless powders. bp is a mix charcoal, sulfur and potassium nitrate. it is NOT an efficient gunpowder, but it IS a sensitive explosive that is almost a requirement for flintlock ignition where bp subs are quite inferior. it will typically be less corrosive than bp subs and easier to administer for fouling control and clean up.
the original king of bp subs is pyrodex, which is a mix of three essential ingredients that contains potassium perchlorate in addition to charcoal, sulfur and potassium nittrate, and other ingredients that are proprietary secrets. all the other bp subs contain NO sulfur or potassium nitrate and are wholly synthetic by nature. these bp subs work mostly via expanding gas rather than as an explosive, and they contain added ignition ingredients. ALL bp subs are classified by the DOT as "smokeless". some of these bp subs produce much higher pressures than real black powder.
*ALL* brands of real black powder are made with just those three ingredients - charcoal, sulfur and potassium nitrate. the essential differences between different brands is the type of charcoal used, the purity of the sulfur and potassium nitrate, and the proportions used in their mixing. this has nothing to do with granulation size, which is a selection based mostly on caliber and function.
*ALL* brands of bp subs are totally different in their characteristics of chemical composition, loading, shooting, fouling control, and clean up. if you change brands and "models" of bp subs, there may be changes required to the load and subsequent performance.
as to making black powder, you really Really REALLY need to know exactly what yer doing, for critical safety reasons. and even then, what you've cooked up will more than likely be inferior to any commercial bp, and will cost a bunch of money and time. just buy the stuff, it's safer.
moving on to a flinter will bring up serious ignition problems that will only be solved with real black powder. i've already posted about how best to acquire the holy black.
getting yer feet wet in trad ml's with a caplock is a good thing because as mentioned it will be easier than a flinter for many logical reasons. it's actually much closer to the early metallic cartridge single shot rifles.
if you are unaware of the following, i would be remiss for not mentioning it. the only other consideration to be aware of with trad muzzleloaders is what guns are offered offshore and onshore. almost all offshore trad ml's will have a "patent chamber" - this is an ante-chamber before the actual chamber that holds the patched ball. when powder goes down the tube, it will first fill up the ante-chamber with between 15 and 30 volumetric grains. let's say we're loading a .50 GPR caplock rifle. a base charge will be about 50 grains of whatever powder, real bp or sub. 30 grains goes into the ante-chamber and 20 grains spills out into the real chamber. the patched ball is seated. a cap is on the nipple, you drop the hammer and the gun goes off. good. the entire barrel is coated with fouling residue, from the ante-chamber to the muzzle. there are more than a few factors that will dictate whether fouling control is or is not required.
IF you immediately load up again, the poured powder goes down into a dirty barrel, and as the patched ball goes to seat on the powder charge, it will scrape some of the fouling crud onto the powder as well. so here's the point of all this - there will come a time, perhaps after a few shots or a dozen shots or even after every shot, that fouling control must be administered. so, down the tube goes a patch (that might be saliva or water or oil or whatever moistened) over a bore sized jag, which can't enter the ante-chamber but will push the crud into it, which will probably not be a good thing for ignition (cap or flint). therefore, out comes a .32 or .36 brush that's draped with a moistened patch (that was swapped for the jag), and it gets into the ante-chamber and swabs it out. there *might* also be a need for dry brush and jag patches, too.
another consideration is that since there can be no airspace between patched ball and powder, if your offshore gun's ante-chamber holds 30 grains of powder, it would mean that no less than a safe 35 grains be the minimum charge for that gun. charging less would probably barely fill the ante-chamber and create that powder/patched ball space.
almost all onshore built guns, rifles and smoothbores, employ classic, traditional flat breech plugs and no ante-chamber. there will be no added fouling control or cleaning required for an onshore gun.
