Question:

The Neck Sizing Bushing that I use for my "Type S" Die is not sizing my case necks to the diameter written on the bushing.  Is my bushing undersized / oversized?

Answer:

While it is possible that a Bushing's inside diameter is incorrect, it is very unlikely.  In fact, our bushings are good enough that some folks use our bushings as an "ID standard" to set inside diameter measuring instruments.  We Sunnen hone all of our bushings to a tolerance of -.0005 inch.  (For example, a .333 diameter bushing will measure no larger than .3330 and no smaller than .3325, usually about .3327 to .3328). 

It is very common for reloaders to measure the inside diameter of their bushing with a dial or digital caliper.  Because the inside surface of a bushing is circular, the flat surfaces on the inside jaws of a caliper cannot be used to obtain accurate measurements (known as bridging).  Not to mention the fact that even the best calipers are only accurate to +/- .001.  Using precision ground I.D. Plug Gauges is the only way to accurately measure the I.D. of our Bushings.

Likewise, one cannot measure the neck of a "sized" piece of brass to determine a bushing's size.  Because of springback and the metallurgic properties of brass, the neck of a sized case will not reflect the exact inside diameter of the bushing that it was sized in.  Because of the case differences, both new and as they work harden with age, most serious handloaders end up with several bushings to control bullet tension (bullet pull) closely. 

As always, Redding is happy to examine a bushing that appears defective.  Should we find that the bushing's inside diameter is incorrect, it will be replaced under our Warranty with no questions asked.  Please contact us before mailing any product to us for warranty inspection so that we can be sure that we are solving the difficulty you are having.