George A. Hoyem, Volume 3, shows (in addition to the (3 and 3 1/4 inch) .500 cartridges in lengths of 1 1/2, 2 1/4, 2 1/2 and 2 5/8 inch.
All are of Boxer coiled case construction with iron base discs like the original .577 Snider and .577/.450 Martini- Henry rounds.
They may have been designed to drop into the short breech of Snider sporting rifles.
He does not show any solid drawn cases , which suggests they did not stay current for very long.
He does not give any load data but mentions in relation to the 2 1/4 inch that prison guards in New South Wales were reported to use double rifles (“There’s posh for you!”) in a similar calibre.
The dimensions he lists for the 2 1/2 inch are .653 rim, . 580 head, .546 case mouth, .505 bullet diameter, case length 2.5 inch and OAL 2.81 inch. He pictures two 2 1/2 inch cartridges, one with a short round nose solid (presumably the 2.81 inch OAL) and the other with a longer tubed Express bullet.
It would appear to be dimensionally similar at the base to the 3 inch drawn case which will probably work with trimming and neck reaming but look to see if there is a slight step in the chamber to accommodate the base cup of the coiled case.
Hope it turns out to be a shooter Baz, and welcome to the forum!
