What brand of hulls do you have. A long time ago I loaded some Alcan/Fiocchi brass shotshell hulls. The primers for them were listed as 6.45P. I never actually mic'd any of them but 6.45mm does calculate to .254" (.25394"). Some of the Brazillian import hulls once sold by Navy Arms & then MagTech before they switched to the L Pistol primer also used a 6.45mm primer. The two would however not interchange, one of them had a taller anvil & the primer disc was thinner, but I don't recall which one was which. There are also some rifle primers of the 6.45mm size which have deeper pockets in the case & the primer cups are likewise deeper. You have to make certain you get the proper one as all of them of the same basic diameter are not necessarily interchangabe.
