How to Ruin Your Brass (Without Even Knowing)
Recently 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, 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. What happens is, when you run the case up into the die, the shaft can actually push 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. All you need is for the pin to extend through the flash hole far enough to knock the primer out. The photo show a Lyman Universal decapping die. But the same thing can happen with any die used for decapping.
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. We had a full-length die set up to give .0015″ shoulder bump when used with a turret press. When that same die was switched into a more rigid Rockchucker press that had less play and “thread slop”, the die bumped the shoulder over .004″. We had to back-off the die and re-set the lock-ring to maintain the proper bump.
