tinker, what you need is a russian girlfriend. the tula cartridge factory is making 16/70 brass but is not willing to export other than you have to order a truck load. to bad, its fine brass.

tula 20/70 cbc 16/65 tula 12/70
barnaul dont make the crome platted steel cases in 16 bore http://www.barnaulammunition.com/shotgun.htm