Removing Primer Pocket Crimps

All military brass and some commercial ammunition has crimped or “staked” primers. The crimp helps to hold the primer in when headspace is deliberately loose or just got that way. Military ammo can get a rough ride and anything to hold it together – from crimps to tar bullet seals – helps. This crimping process leaves a thin lip of brass displaced onto the edge of the primer to secure it in place. Before a case that has a crimped primer can be reloaded, the brass lip around the primer pocket must be removed. The old primers push out, maybe reluctantly, then the new ones don’t want to go in. So you have to get the crimp out. But how? What’s the Best way?

There are two methods of removing the crimp or opening up undersized primer pockets; Reaming and Swaging.

Reaming utilizes a cutter to remove the crimp by simply cutting it away. This requires a specially designed cutter. You can’t just use a case mouth chamfer tool … although I’ve seen it done but with poor results. It is far better to purchase a tool designed specifically for reaming primer pockets. There are many reamers available and virtually every press and die manufacturer makes one. They range from simple hand tools to elaborate motor driven units that perform multiple functions in addition to reaming the primer pocket. The singular advantage of reaming is that it can be done with a simple, inexpensive hand tool … no electricity, no press, nothing other than your hands.

Swaging re-forms the entire pocket and produces the easiest-to-insert primer experience. Swaging utilizes a hardened steel stud that is forced into the primer pocket, literally pushing the metal back and restoring the primer pocket to its original dimensions. The only downside to swaging is some setup time. There are many different swaging tools made by most reloading manufacturers. It’s up to you to choose what tool is right for you. Or, let us do it for you with our brass processing service.