September 7, 2021
Winchester Pistol Primers displayed on a bench. Photo courtesy UltimateReloader.com.There is an excellent article about primers on the Shooting Times website. Allan Jones’s Mysteries and Misconceptions of the All-Important Primer is a great read. Jones is a true expert. He was the manager of technical publications at CCI Ammunition, Speer Bullets, and Jones wrote three editions the Speer Reloading Handbook.
This authoritative Shooting Times article discusses primer construction and design. Jones also shares some surprising facts about primers, and corrects common misconceptions. Here are some highlights:
Size is important
Useful Trivia: Although Small Rifle primer pockets and Small Pistol primers share the same depth specification (0.008 to 0.009 inches), Large Rifle primers and Large Pistol primers differ. The standard pocket for Large Pistol primers is slightly smaller than its Large Rifle counterpart. It measures 0.008 to 0.09 inches.
Magnum Primers
You can make Magnum primer in one of two ways. Either use more of the standard chemical mixture to produce a longer-burning flame, or you can modify the mix to give it more aggressive characteristics. CCI used the first option for Magnum Rifle primers prior to 1989. We switched to a mix that was optimized for spherical propellants. It produced a 24% rise in flame temperature, and a 16% increase in gas volume.
Foiled Again
A lot of component primers have a little piece of paper between the anvil & the priming mixture. It’s called “foilpaper” because it replaces the original metal foil used to seal early percussion caps. This little disk is only there for manufacturing convenience. The inside diameter of the cup is smaller than the wet primer pellets. They must be compacted to reach their correct height and diameter. The foil paper is essential as the wet mixture will stick to the pins and jam up during assembly.
ShootingTimes.com – Full Primer Story
VIDEOS ABOUT PRIMERS
These videos provide basic information about primers.
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Tags: Allan Jones. Foil, Gun Digest. Ignition. Magnum Primer. Primer. Primer Cup. Reloading. Shooting Times. Speer.
