Here's my favorites for this caliber.
For a moderate load with suprising power, try a 300 grain boolit over 6.5 grains of RED DOT. I get 900fps and OUTSTANDING accuracy from my 5.5" blackhawk.
For a full power, hard hitting, LARGE game hunting load, I use the same boolit over 18 grains of 2400. A word of caution about this load. Keep an eye on your gripframe screws. This load generates enough recoil that if they are loose and the grip can flex, it WILL crack the gripframe over time. This is not a plinking load, but if you're headed out to kill a moose,elk, bear, etc... it WILL get the job done.(I shot through 2 hogs with one of these last year)
For a load that will whistle right through any whitetail or medium game, try the classic 9 grains of UNIQUE under a 255 grain Keith SWC. I shot an antelope 2 years ago with this load and it penetrated diagonally lengthwise. The previous FOUR shots that I took and missed at the SAME antelope at 40 yards, made impressive holes in the prairie.(Nothing like handgun hunting to keep you humble)
For a nice sedate target load, for rolling cans or busting rocks, I use 6.5 grains of RED DOT under a 255 keith swc. I get 850 fps from my blackhawk, and sub 1" groups at 25 yards. This is also the load I'd suggest to anyone who has a lady or youngster hunting with a 45COLT levergun.
The recoil and blast from this load makes a 243 seem like a 416 rigby in comparison.
The above mentioned 6.5 grain load with RED DOT and a 300 grain boolit is also a GREAT hunting load from a carbine.
I've had lots of people doubt it's power due to the low blast and recoil. I change their minds when I have my daughter blow a hole clear through an 8" tree with them.
18.5 grains of 2400 under a 255 keith swc is another classic I've played with. Velocity runs around 1100fps from my blackhawk and 1500 from my win 94 carbine. I'm a cheap SOB and don't shoot this load much, as I can get nearly the same velocity from other loads that use less powder.
For a fun small game load I load a tumble lubed .454 round ball over 5 grains of RED DOT. I get 590fps and itsy bitsy groups from it. I recoils about like a 22rf from my carbine and is my daughters favorite load. I've shot a few grouse with it from my blackhawk and it puts them down nicely, and doesn't rip up the meat like a SWC does.