The Dillon .44 Spl, .44 Mag Steel Handgun Crimp die is used for reloading .44 Spl and/or .44 Mag ammunition. Dillon crimp dies use a taper crimp for semi-auto pistols and accu-crimp for revolvers. Dillon dies have standard 7/8"x14tpi threads, and are designed to work best on Dillon progressive reloading machines. The new 1" lock rings allow a little more space on the tool head (when adjusting the dies) for the 1" wrench to fit.