I will chime in here, since I regularly load and shoot .45 Colt BP loads. It's a hoot and darned easy, too!
First is the case capacity. Different brands of cases have different capacities: Starline holds more than Winchester. I prefer Winchester cases for that reason, although someone shooting reduced loads might do well with the Starline.
When I first loaded the cartridge that way, I tried 40 grains of 3Fg and it, sure enuff, was a very stout load. Modern guns will not have any trouble with it. The original problems were twofold: the cast iron frame guns that Colt first put out would not stand the load and the mounted troops could not control the load on horseback. Hence, the drop to 30 grains.
With the 40 grain load, I tried seating the soft (1:20 T:L) bullets by themselves to produce the compression, but it deformed the bullets too much. Then I went to a separate compression die and used it, compressing enough to get the bullet seated properly with no air space. That worked well enough and allowed me to shoot different bullets.
It became apparent that 3Fg powder would foul my guns very quickly, so I tried 2Fg and the fouling settled down. I read where the Frankford Arsenal loaded the cartridge, 'way back when, with what was the equivalent of 2.5Fg. I tried a mix of equal parts of 3Fg and 2Fg to make it and sure enuff, it was a decent compromise between velocity and fouling. Now Goex makes the "Cartridge" grade powder, which is essentially the same.
Do not waste your money on hard bullets with hard lube. Be sure to shoot soft bullets, sized to fit the cylinder throats, that have a soft, gooey lube. That combination gives the best results.
Use a hot, regular primer like Winchester.
You don't really need much compression to get good results and anything that does not absorb moisture is fine for use as a filler. I use grits and they work fine, what with their large granules and so on.
Lately, I have been using hollow-based bullets cast 1:20 on top of about 30 grains of 2,5Fg powder. It is a decent load: it does not lead, it really goes boom, and it gives enough recoil to be convincing. Do try bullets from
www.cowboybullets.com . They have soft bullets with soft lube and they shoot well. Hollow based bullets, like the originals, are a do-it-yourself proposition.
