How to Properly Set Up and Adjust Decapping Dies

One of our Forum members complained that he wasn’t able to set his primers flush to the rim. He tried a variety of primer tools, yet no matter what he used, the primers still didn’t seat deep enough. He measured his primers, and they were the right thickness, but it seemed like his primer pockets just weren’t deep enough. He was mystified as to the cause of the problem.

Well, our friend Boyd Allen diagnosed the problem. It was the decapping rod. If the rod is adjusted too low (screwed in too far), the base of the full-diameter rod shaft (just above the pin) will contact the inside of the case. That shaft is steel whereas your case is brass, a softer, weaker metal. So, when you run the case up into the die, the shaft can actually stretch the base of the primer pocket outward. Most presses have enough leverage to do this. If you bell the base of the primer pocket outwards, you’ve essentially ruined your case, and there is no way a primer can seat correctly.

The fix is simple. Just make sure to adjust the decapping rod so that the base of the rod shaft does NOT bottom out on the inside of the case. The pin only needs to extend through the flash hole far enough to knock the primer out. The photo shows a Lyman Universal decapping die. But the same thing can happen with any die that has a decapping rod, such as bushing neck-sizing dies, and full-length sizing dies.

Whenever you use a die with a decapping pin for the first time, OR when you move the die to a different press, make sure to check the decapping rod length. And it’s a good idea, with full-length sizing dies, to always re-check the height setting when changing presses.

There are a variety of decapping dies currently on the market, with models available from LEE, Lyman, Hornady, RCBS, Redding, and Sinclair Int’l.

LEE Universal Decapping Die Costs Just $11.49
Speaking of decapping tools, Midsouth Shooters Supply sells the LEE Universal Decapping Die for just $11.99 (item 006-90292), a very good deal. There are many situations when you may want to remove primers from fired brass as a separate operation (prior to case sizing). For example, if your rifle brass is dirty, you may want to de-cap before sizing. Or, if you load on a progressive press, things will run much more smoothly if you decap you brass first, in a separate operation.

Decapping Dies for Cases with Smaller Flashholes

TAKE NOTE: Some Euro Small Flash Holes are spec’d at 1.5mm or 0.059″, and max out at about .062″, so these need a smaller die pin.

The low-cost LEE Universal Decapping Die will work with cartridges from 17 Fireball all the way up to big Magnums. However, NOTE that the decapping pin supplied with this Lee die is TOO LARGE for LAPUA 220 Russian, 6mmBR, 6.5×47, 6.5 Creedmoor, .308 Win (Palma) and Norma 6 PPC flash holes. Because the pin diameter is too large for these brass types, you must either turn down the pin, or decap with a different tool for cases with .059-.062″ flash-holes.

Sinclair Int’l offers a Stainless Decapping Die that comes with BOTH .080 and .060 Pins. The $46.99 die ships with three decapping pins for standard .080″ flash holes, and two pins for .060″ flash holes.

Redding makes a Universal Decapping Die with an optional smaller-diameter decapping rod for the smaller .059-.062″ flash holes found on the BR and PPC cases. The use of this die is explained in the video below: