July 19th, 2021

Tech Tips for Priming Cases More Efficiently and Safely

Primer Forster Co-ax priming tool
The anvil is the tripod-shaped thin metal piece protruding above the bottom of the primer cup. Getting the primer sitting fully flush on the bottom of the case primer pocket, without crunching it too much, requires some keen feel for the progress of primer seating.

top grade ammo book Glen Zediker

Sadly, Glen Zediker passed away on October 1, 2020. But his technical insights and helpful advice live on thanks to his written works — his books and articles. In two informative Midsouth Blog articles, Glen Zediker presented helpful advice on priming. First he examined what happens to the primer itself as it is seated in the cup. Glen then explained why some “crush” is important, and why you never want to leave a high primer.

Glen also reviewed a variety of priming tools, including his favorite — the Forster Co-Ax Bench Primer Seater. Then he offers some key safety tips. Glen provides some “rock-solid” advice about the priming operation. You’ll find more great reloading tips in Glen’s Top-Grade Ammo book.

Priming Precision vs. Speed
Glen wrote: “The better priming tools have less leverage. That is so we can feel the progress of that relatively very small span of depth between start and finish. There is also a balance between precision and speed in tool choices, as there so often is.”

Benchtop Priming Tools — The Forster Co-Ax
Glen believed that the best choice among priming options, considering both “feel” and productivity, may be the benchtop stand-alone priming stations: “They are faster than hand tools, and can be had with more or less leverage engineered into them. I like the one shown below the best because its feeding is reliable and its feel is more than good enough to do a ‘perfect’ primer seat. It’s the best balance I’ve found between speed and precision.”

Primer Forster Co-ax priming tool

Primer Forster Co-ax priming tool

Load Tuning and Primers
Glen cautioned that you should always reduce your load when you switch to a new, not-yet-tested primer type: “The primer is, in my experience, the greatest variable that can change the performance of a load combination, which is mostly to say ‘pressure’. Never (never ever) switch primer brands without backing off the propellant charge and proving to yourself how far to take it back up, or to even back it off more. I back off one full grain of propellant [when I] try a different primer brand.”

Primer Forster Co-ax priming tool

Priming Safety Tips by Glen Zediker

1. Get a good primer “flip” tray for use in filling the feeding magazine tubes associated with some systems. Make double-damn sure each primer is fed right side up (or down, depending on your perspective). A common cause of unintentional detonation is attempting to overfill a stuffed feeding tube magazine, so count and watch your progress.

2. Don’t attempt to seat a high primer more deeply on a finished round. The pressure needed to overcome the inertia to re-initiate movement may be enough to detonate it.

3. Keep the priming tool cup clean. That’s the little piece that the primer sits down into. Any little shard of brass can become a firing pin! It’s happened!

These Tips on Priming come from Glen’s excellent book Top-Grade Ammo, available at Amazon.com.