I have loaded a full case of Hogsdon triple 7 FFFg and the Lyman #314299 gas-checked bullet to duplicate the original black powder load for the .303 British cartridge in my Martini-metford and Lee Metford MkII rifle. I was able to obtain 1850 fps with only slight compression. The load was 70 grains volume of T-7 3-F. Accuracy was reasonable as long as I ran a damp patch down the bore every 5 shots. Triple seven is slightly more energetic than real black powder and is known for the famous "crud-ring" that forms in the throat, necessitating the damp patch. The rifles both shot to the sight graduations out to 300 yards which is all I have access to around here.