A primer about primers

Monday, December 11, 2006 Filed in: Ammunition, Gunsmithing
When doing action work, I ask my clients how they'll be using the gun. For instance, a competition shooter who handloads their own ammunition can utilize a lighter action than someone who needs the gun to work with a variety of factory ammunition.

Why is this? Well, primers are not created equal - the brands vary in terms of their sensitivity. Some of this is due to the type and thickness of the metal that the cup is made from, but there is also some difference in the primer material itself.

In general, Federal primers are the easiest to ignite; their cup material is slightly thinner, and softer, than their competitors. Combined with a primer mix that is well known for its sensitivity, they require less force to "pop." This translates to being able to use a hammer with a lighter mainspring, which allows for a lighter trigger pull.

The primers generally conceded to be the most difficult to ignite are CCI brand. Their cups are hard and thick, and require a real "wallop" to work properly. This means that the action is going to need full-power springs, with the increase in trigger pull that they bring. Winchesters fall in the middle, slightly more to the Federal half than the CCI.

In any brand, the magnum version of the primer will be more difficult to ignite. This is because they typically have harder and/or thicker cups to withstand the higher pressures that heavier loads deliver.

This isn't the end of the story though. The Czechoslovakian Sellier & Bellot ammunition uses what may be the hardest primers made. Sometimes even the heaviest, hardest-hitting hammers are insufficient to set this ammunition off, and is one of the reasons I recommend you stay away from it. CCI Blazer ammunition is known for being unreliable with lighter actions, as is the "green" or non-toxic ammunition that's on the market today.

Back to action work...when someone tells me that the gun is for self-defense, that usually means that utmost reliability is desired. To get such reliability, it's imperative that the gun work with any kind of ammunition that one might find on the shelf. In these cases, I test the gun with CCI Magnum primers - the hardest-to-ignite primers that you can get outside of the aforementioned Czech fodder. If the gun will reliably detonate the CCI Magnums (with zero failures), it should ignite anything you're likely to encounter.

On the other hand, if the requirement is for a light competition action I'll test the gun with Federal primers; if I've done my job right, such a gun will shoot Federals perfectly, Winchesters somewhat less reliably, and CCI primers very badly. That's the price for a low trigger weight!

This brings up another topic: that of live fire testing. I'll leave that for another day, as I've got a story to tell!

-=[ Grant ]=-
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