One of the most important aspects of precision reloading is setting the shoulder bump during the full-length (FL) sizing process. You want the amount of “bump” to be precise and identical for every loaded round. However, when you switch brands of brass you may need to change the die position to get the desired bump and case body sizing. And even with the same brand of brass, you may find that you need to adjust your FL die as the number of brass load cycles increases. Brass that has been fired many times will behave differently than new or near-new brass.

Also, even with the same cartridge type, brass loaded for a semi-auto rifle may need more bump than brass fired in a bolt gun. For example, with .223 Rem ammo, you’ll normally want to push the shoulder back farther if the ammo will be shot in a AR15 as opposed to a bolt-action rig.

So how do you make all these needed adjustments for your full-length dies? You can move a conventional locking ring up and down, but that can be a tedious, trial-and-error process. Some guys use shims in one-thousandth intervals, but that still requires taking your dies in and out of the press. Well there is a better way now…

PMA Tool Micro-Die Adjuster

Wouldn’t it be great if you could precisely adjust your FL die up and down in half-thousandth increments, with a simple indexed click. That is now possible with products offered by PMA Tool and Whidden Gunworks. PMA Tool offers a Micro-Die Adjuster that replaces your existing lock ring and can be used with nearly any 7/8-14 full length sizing die. The engraved marks correspond to approximately .001″ of shoulder bump adjustment. Splitting the engraved marks is therefore approximately equal to .0005″ (half a thousandth). Users love this product, saying it adds precision and saves time.

Whidden Click-Adjustable FL Sizing Die System

Whidden Gunworks offers a complete click-adjustable FL sizer die with a special, indexed ring. With Whidden’s patent-pending Click Adjustable Sizer Die system, the die and lock ring work together to allow rapid, precise bump adjustments. One click changes the bump .001″. It’s simple and fast. Included with the Click Adjustable Sizer Die is a shoulder bump gauge. John Whidden (in video below) explains:

“There has become a need for an easier way to adjust the sizer die properly. Until now there have been few options other than trial and error to get the shoulder setback correct. Anyone who has done this can attest that it’s a slow and imprecise job! Our die and lock ring work together to give the user a clicking feel to the adjustment. Each click moves the shoulder bump .001” so you can easily find the exact shoulder bump that you desire.” — John Whidden

General Tips on Setting Up and Using Sizing Dies