Heat treated steel neck sizing bushing fits Redding Competition and S-type sizer dies. The sizing diameters are hand-polished with a surface hardness of Rc 60-62 to reduce sizing effort. To determine your bushing size, measure the outside diameter of your cartridge neck with a bullet seated. Subtract .001" from that measurement to get your bushing size.
Redding Neck Sizing Bushings have a external dimension of 1/2" OD X 3/8" long. They are available in .001" size increments. By selecting the correct bushing, you are then able to provide just the right amount of neck tension to properly hold the bullet without excessive resizing. These are clearly marked with the size I.D.
Determining Redding Bushing Size
The proper bushing size can be easily determined by measuring the outside neck diameter of your loaded cartridges with a precision micrometer or a dial caliper. Then, simply subtract .001" from the cartridge that had the smallest average neck diameter. This diameter bushing will generally size case necks just enough to create the proper press fit for the bullet.
If you are using a Type “S” style die and not turning the outside of your case necks, we suggest using a bushing .002" smaller than your smallest average neck diameter, and using the expander ball included with your Type “S” die. This size bushing will still give you minimal sizing (maximizing the life of your brass) and the expander ball will insure that each cartridge has the same bullet grip.
Redding has found that when you have cases with neck wall thicknesses on the thin side of the SAAMI tolerance, your fired case will measure considerably larger (.006" to .010" larger) than your loaded rounds. In these circumstances, Redding’s tests have shown that a bushing .001" larger (than the loaded round) may give you the desired bullet grip.
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