Hi Raimey,
I'm still getting to grips with how the forum works...and what the various ID's are!
Herr Haggards doesn't mention anything about the tube lengths, but I will ask.
I'm just looking into what would be a safe cartridge to try in it, the 65mm Gamebore Regal 28g no.6 seems to be the one recommended for older guns. Any thoughts?