Howdy

The whole reason Trail Boss was developed in the first place was for light loads in big, cavernous cases like 45 Colt. It was developed specifically with Cowboy Action Shooters in mind. That's why it has the 'old west' name. A lot of CAS shooters were trying to duplicate 38 Sp ballistics in the 45 Colt, with light powder charges and light bullets. 45 Colt does not take well to that, 3 flakes of Whiz Bang tends to burn erratically with so much empty space. Trail Boss was developed specifically to take up more space in big cases for light loads.

I have messed around with it a bit, but frankly, I prefer to stuff the 45 Colt to the brim with FFg. If you think Trail Boss is expensive, try dumping 35 grains or so of FFg in each cartridge.