Bill, there are just three loadings for this calibre in Black Powder given in Bill Flemings superb book "British Sporting Rifle Cartridges". 1993. This was a private publication and is hard to get, all the copies that were printed have been sold and I have heard nothing of a reprint.
I'd be very wary about using any powder other than BP. The Holy Black was what this rifle round was designed for and the rifle built to withstand. The makers of Blackhorn 209 recommend the use of a small charge of BP over the primer to boost the reliable ignition of this powder.
Bye the bye, all lead bullets used in this rifle were paper patched and not grease groove, Metford rifling was also designed for use with paper patch bullets, so don't handicap yourself by using anything other than PP bullets.
Fleming lists three loads as follows :- In all instances 130 grains of BP are listed for the following bullet weights for 300, 340 and 380 grain lead paper patch bullets.
Do not use modern jacketed bullets of any type. Don't be put off using BP, Metford rifling is very easy to clean even using BP. Ivariably Curtis and Harveys No.6. Sporting Powder was used in F or FF granulation, (production ceased in 1976 and it is no longer made anywhere). Please use proper BP not an imitation, and use nothing finer in granulation than FF.
Fleming lists eight other loads with bullets weighing from 340 to 440 grains but with powder charges of Cordite, Axite or The Smokeless Powder Rifle Co's. Rifle Powder. All these were early nitro loads introduced after your rifle was made and there are no modern equivelents. The Black Powder barrels of the time were made of a soft steel and it was easily erroded and worn by high temperature powders and guilding metal bullets.
Enjoy using your rifle, but please use the correct powder and bullets.
Harry
Last edited by Harry Eales; 08/23/11 03:06 AM.