"Interesting story to the gun. Nice to be able to put some 'flesh on the bones'. When that gun was made the .410 was only available in 2" so the chamber length would not be mentioned. The 2 1/2" came in around 1913 and the 3" around the late 1930's. Eley certainly still make 2" cartridges as do some other European makers. Of course this will be a black powder era gun. Lagopus.....