I finally was able to pick up my BFR in this caliber. I have Starline brass and the Lee 300-grain mold. Thought I would look for a Trail Boss load for cutting holes in paper. Anyone have a favorite just-for-fun load they find accurate with a moderately heavy cast boolit and TB or another powder? Looking for loads running 800-1,000 fps.

The Lyman Cast Bullet Handbook is a good source on info. Or check out the Freedom Arms site. The load data is at the bottom in a PDF file.

I like Unique. For really low power loads you can use the .45 Colt data. For a little hotter load, use the .454 Casull data.

The case volume difference between the two is small. The Casull is longer, but the web is so thick it negates the length difference. The small rifle primer adds a little velocity, but you are so far under max pressure, I've had no issues.

10gr of Unique behind 300gr Lee cast bullets of wheel weight lead gets me to about 1125fps. A jacketed 300gr bullet and this load hits about 1000fps. This is in a 4 5/8" converted Blackhawk.

Jeremy

I use thisIts a pussycat load.
300 GR. CPB LFN GC
Starting Loads Maximum Loads
Manufacturer Powder Bullet Diam.
C.O.L.
Grs.
Vel. (ft/s)
Pressure
Grs.
Vel. (ft/s)
Pressure
IMR Trail Boss .452" 1.800" 6.5 767 14,900 CUP 8.0 865 23,900 CUP

I don't own a Casull but I shoot the same bullet out of my Blackhawks and use Unique. It's my go to powder for light loads in the Colt. I use 8gr for the 300gr Lee and 9gr for 255gr bullets. I see no reason you couldn't use 10grs in your Casull.

Thanks fellas. Guess I better load up a batch with Unique and a batch with Trail Boss and head to the range. I really prefer Universal Clays to Unique, but it has been virtually unobtainable in these parts.

I use 10 gr. of Longshot under a 340 gr WLN in Colt cases for about 850 fps. Try 11 gr. with the 300.