There were apparently several 'light nitro' loads for the .577 x 2 3/4: the 65gr Cordite load equalling the original BP cartridge, a 75gr Cordite load, and the 90gr Cordite or 'full nitro' load.

There was also a 750gr projectile load for the 2 3/4 case.

Here's my take on the .577 x 2 3/4 cartridge, for those who haven't seen it before: .577 Light Nitro

John: I wouldn't let a decent 2 3/4 chambered .577 double get away if I were you. They are simply marvellous things.

As an aside: a well-known A&N Webley screw-grip double in the Northern Territory (known as 'Stumpy' due to the shortened barrels following an accident!) was originally a 65gr Cordite gun, but was re-regulated for the 90gr load when the surgery was performed. Eventually the ribs sprung loose (!) and it has now been sensibly restored to its original regulation.