Die blanks allow you to cut a die for a custom chamber dimension or to create a new die for a wildcat cartridge. They must be reamed with a die reamer (sold separately) and are pre-drilled with a pilot hole for the caliber listed. (Unpiloted version has just a .250" pilot hole drilled to hold the blank on the lathe.) Standard 7/8 x 14 threads to fit most popular reloading presses. Dimensions:Length = 3.875" Width = 3/4" Features:Standard 7/8" x 14 Thread SizeKnurled Upper Notes: Not a finished die. Must be reamed to the cartridge specifications of your choice.Upper end must be drilled and tapped for internal die parts such as the decapping/expander unit as well as the seater stem (available from RCBS).Lock ring for setting the die for a desired cartridge length not included (available from RCBS).Pilot hole of listed caliber drilled through die bodyDie body is made of the same material as used by RCBS and other manufacturers. Heat treating is generally not necessary as the die body...