Bit late, sorry, but in response to:
".577x 3 1/4"......??? whats this? i have heard of the cordite round,but never the BPE round....."

empirevr:
Check on page 152-153 of Fleming's text, he lists 5 load combinations, with 160 or 167 gr BP and 560, 610, and 650gr lead bullets. Hoyem lists it on page 52 of his text, showing 4 patterns: the BP Express, the 'N-for-B', and two full nitro loads.

If you don't have these two books, I might recommend adding them to your library. They are pure gold as far as British Sporting cartridges are concerned.

"The History and Development of Small Arms Ammunition: Volume Three: British Sporting Rifle" by George A. Hoyem

"British Sporting Rifle Cartridges: a Summary of Case Types, Headstamps, Bullets and Charge Variations" by Bill Fleming