John Whidden’s Tips for Selecting Bushings For Bushing Dies

Whidden Gunworks produces excellent sizing and seating dies. The Whidden full length sizing die with a neck bushing is popular because you can “tune” neck tension using different bushings with larger or smaller inner diameters. John Whidden explains in this video how to select the right bushing for your neck-sizing die and full-length bushing die. John Whidden suggests that for most applications you start with the outside diameter measured by calipers of a loaded cartridge, (with your chosen bullet), and then subtract about three thousandths. If your round mics are loaded at.333 then you should start with a 0.330 bushing. John says that you can experiment with bushings by going down and up by a thousandth. As your brass ages, and the necks become harder, you may also want to change bushing sizes. Quick Tip: Flip Your BushingsYou can also “flip” your neck bushings so that the side that contacts the case’s neck first is different. The bushings are usually marked on one side with the size and unmarked on the other. Try “number-side up” and “number-side down”. Some people believe that the bushing on one side may allow for a smoother entrance, which can improve concentricity. Some people believe that the orientation of the bushing can produce a very slight increase or decrease in neck tension. It is a subtle but noticeable effect. Experimenting with it is free. If you find that one orientation of the bushing is better, you can mark it with nail polish to ensure you always have the bushing oriented optimally. NOTE: We’ve confirmed that some bushings have a slight taper. Bushings can also be slightly distorted when the brand and size are stamped. There IS a good reason to try both orientations.