how is the head space measured on a rimmed cartridge in a sxs double rifle in referance to the base of the cartridge to the standing base of the frame and what are the tolerances? thanx

it depends .. the datum is rim thickness, and its some stated over maximum stated rim thickness ... 1-5 thou...anything more than 5 thou is TODAY considered to be no-go

thanx: that is my problem [ the rim thickness] the cartrige is an odd ball and i had to form them from ,348 winchester brass. it fired and regulated fine but after about 40 shots it came off face.that has been corrected and now i want to locate basic brass with the proper rim thickness and check the head space. but i dont want to invest a lot of money in bell brass etc to find myself back in the same place. im also very concerned of making the same mistake again. any suggestions? regards