Caliber confusion…

Guns Magazine, July, 2004 by Dave Anderson

"A beautiful buck walked past me. I aimed carefully and squeezed the trigger. In an instant. I was blinded by smoke and stunned by an explosion ... I had loaded a .308 cartridge in my .270 rifle. The gun was damaged beyond repair. The stock was broken, the magazine blown out, and the barrel torn to shreds."

The passage is from a letter published in a 1964 issue of Outdoor Life Magazine. In the years since I've heard of several similar incidents. Such as: .270 Win. cartridges being fired in 7mm Rem. Mag. rifles, .30-30 Win. cartridges in .303 British rifles, .223 Rem. in .22-250 Rem. rifles.

When a cartridge is fired the case expands to grip the chamber walls, forming a gas-proof seal. If the case is too small in diameter, too short (or both) it will keep expanding until it raptures. Once the integrity of the seal is broken, powder gases are free to rash back into the action.

The danger of using incorrect ammunition for the firearm in use is well known. Yet it happens, and to people who know better. A few examples illustrate how to reduce the risk of it happening to you.

Common Sense Precautions

A spare rifle in camp is a good idea, but as the example above shows it can result in cartridge mix-ups. To reduce the risk, use different methods to store and carry ammo--perhaps a belt slide with loops for cartridge "A," a folding ammo wallet for cartridge

A friend was on a prairie dog shoot along with a couple of companions, father and son. Dad's rifle was a Remington 700V in .22-250 Rem., son's another 700V in .223 Rem. Both were shooting prone, with their ammunition in identical cartridge boxes on the ground between them.

Dad inadvertently grabbed a round from the wrong box and loaded a .223 round in his .22-250 rifle. How the round fired I cannot really understand. I tried loading an empty (but resized and primed) .223 case in my own 700 and couldn't get the primer to pop.

At any rate, the round did fire. The .223 case, expanded and ruptured, was later removed from the .22-250 chamber. The shooter was fortunate to be using the very strong 700 action. A small amount of powder gases and brass particles, likely coming down the firing pin tunnel, peppered his face but he suffered no permanent injury.

It Can Happen To You Too

I once made a similar error. One spring day in the early '70s I hurried out to a favorite gopher shooting spot. When I tried to load my Sako Vixen .222 Rem. the round refused to chamber. I tried another round, and another, with similar results. I scowled at the cartridges for a moment, wondering what was wrong with my reloads, then suddenly realized I was trying to load .223 Rem. amino in my .222 Rem. rifle.

At the time I stored ammunition in neat stacks on a shelf, starting with the smallest calibers on the left and working up. That left .222 and .223 ammo stored side by side, in nearly identical boxes. In my haste I'd knocked over a stack and then grabbed the wrong box. Subsequently I started using MTM cartridge boxes, labeled with big stick-on numbers and letters from a school supply store.

At the shooting bench, it's common to shoot a few groups with one rifle, set it aside to cool while shooting something else then go back to the first rifle. Having more than one caliber on the bench at a time is just asking for trouble. I read of a shooter who did so and wound up firing a .270 cartridge in his 7mm Mag., damaging the rifle but luckily not the shooter or bystanders.

Now when I set a rifle aside temporarily I close up the amino boxes that go with it and put them away in a gear bag before uncasing the next rifle. It takes a little longer but it's time well spent.

Problems arise when cartridges have similar names. I once had to convince a skeptical neighbor nut to use .303 Savage ammunition in a .303 British rifle. A friend gave me a .30-30 case which had been fired in a .303 British rifle.

A reader from an African country, where both rifles and ammunition are hard to come by, wrote he couldn't find .30-30 Win. cartridges for his Winchester 94. Looking in a catalog from a European ammo maker he found the metric designation of the .30-30 cartridge was 7.62x51R. European custom is to designate cartridges by bore diameter and case length, with "R" indicating a rimmed case.

He wanted to know if it was safe to use 7.62x51 ammunition in his rifle. Of course he could not. 7.62x51 is the metric name of the cartridge we call .308 Win. Although bullet diameter and case length are the same as the .30-30, the .308 case is rimless, larger in diameter, has a sharper shoulder, shorter case neck and is loaded commercially to much higher pressures.

The only safe rule is this: the cartridge designation stamped on the barrel should be identical to that stamped on the cartridge case head and on the cartridge box.