The .577/500 No. 2 Black Powder Express, also known as the 12.7mm British No. 2, is a British centerfire fire rifle cartridge.

The .577/500 No. 2 BPE was developed as a black powder round some time before 1879 by necking down the .577 Black Powder Express to .507-inches (12.9 mm)^[2] for use in single or double rifles, as well as a variety of Martini-based lever rifles.

Like the .450 Black Powder Express, the .577/500 BPE came in several case lengths, the most common having a 3-inch case. A 3+1⁄8-inch variant would later be loaded with cordite to become the .577/500 Nitro Express.^[1]

For some time the .577/500 No. 2 BPE was loaded with cordite to become the .577/500 No. 2 Nitro for Black, the same cartridge loaded with mild loadings of cordite, carefully balanced through trial to replicate the ballistics of the black powder version.^[1]

The .577/500 No. 2 BPE was a popular cartridge in India for hunting all thin-skinned game up to tigers.^[1] It did not face competition from comparable .450 rounds there in the decades following 1907 due to the ban on British military calibres. Like the .500 Black Powder Express, the .577/500 No. 2 BPE was never popular in Africa, not being powerful enough for thick-skinned game such as elephants.^[1]

Moderately popular in its day, the round has long since ceased to be offered commercially.

• 12mm caliber
• Express (weaponry)
• List of rifle cartridges
• List of rimmed cartridges

• Barnes, Frank C, Cartridges of the World, ed 13, Gun Digest Books, Iola, 2012, ISBN 9781440230592.
• Wieland, Terry, Nitro Express: The Big Bang of the Big Bang, retrieved 20 Jun 16.

• .577/500 No 2 Black Powder Express, cartridgecollector.net, retrieved 20 June 16.