Semisane

Oops! Almost missed your last question 12Gauge. It's not likely that a .530 ball and .015 patch will be too loose. It may load easily, or may require a rap on the short starter to get it into the barrel. The thing is, all of these barrels are different, and they do change a little with a lot of shooting. The bore gets smoother. the lands become less sharp. The muzzle might even develop a little cone. So the patch/ball combination depends on your barrel and to some extent on your load. You can get away with a thinner patch when shooting light loads. (By the way, during your introductory experimentsI would stick with either Pyrodex or GOEX and avoid T7.)

So, a .530 ball and either an .015 or .018 patch will likely do fine to get you started and comfortable with the gun. Once you're ready to experiment you will want to try some .535 balls too, and different patches to see what works best for you. And then there's lube. The bore butter will be fine to start with and you may like it. If not, there's only two or three thousand other things to try - from spit, to SnoSeal, to Crisco, to Olive Oil, and many more exotic combinations. Playing with this stuff is half the fun.