Colorado - Jeff Tanner, in England, will cut you any size mould you want. All you have to do is to e-mail him with the dia requested. Mine, from him, arrived in 1 week from the order date, along with a bill to send $23.00 US to a California address. The moulds fit any standard handles and while they don't have sprue cutters, the resulting sprue is easily snipped off with wire strippers(my favourite). A quick bvrush with a wood rasp, removes any trace of sprue so they can be loaded without orientation. I use a small dia hole in the strippers for snipping off the sprues - (quick and easy)
: The moulds case about .003" under size, so if a .720" is required, order a .723" mould. These measurements are approximate, as definitve numbers aren't necessary.
: Although recoil goes up radically with heavy charges in large bores, pressure doesn't. A 12 bore rifle actually developes less pressure to obtain 1,300fps than does a .50 or .54 calibre rifle, both shooting round balls. Recoil is the killer for stocks, however, if well made, there shouldn't be a problem. The big bores become nice plinkers with small charges in the 90 to 110gr. range and are more than sufficient for deer and black bear with those charges. Accuracy at longer ranges may suffer with light charges, as it did in my rifle.
Good luck and mail me if I can be of further assistance.
: Set aside the Labour-day weekend (1st Sept) next year for a week-long rendezvous at Heffley Ceek, B.C. just north of Kamloops. There, you can compete against my .69. What fun!