with original brass being available and brass that can be reformed to, i would not rechamber any of my many milsurp rifles. 7.7 japanese can be made from 8x57 mauser just by resizing it in a 7.7 size die. example with 30-30 brass i make 25-35, 303 savage, 32-40, 32spl, 38-55 that allows me to shoot the rifles very cheaply. i buy all the brass i can at flea markets, yard sales and gunshows, i clean it, prep it, size it and store it in air tight containes. i load and shoot some weird calibers in older military and civilian rifles. to me its part of the fun owning old and odd ball calibers and getting them to spit fire and lead again. i also hunt with them. eastbank.