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Out Of Battery Ignition
Subject: .22 shell blew up on me

Posted By: David R - Registered User

Posts: 75

Posted At: (1/10/02 4:14 pm)

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Hi guys, I am at work right now but I will try (key word here is try) to post a picture tonight of the shell casing after it blew out its side.

So, here is the story...

I was playing around with my marlin papoose shooting off some run-of-the-mill KMart special .22 shells when all of the sudden I saw this large flash on the right side of the rifle - the ejection port (for lack of better terminology) - and some pain on my face. Of course the human body's initial reaction is to close the eyes and jerk the head back! I sat there for a second with the adrenalin rush and then looked at my rifle. The shell casing was only partially seated in the chamber. It was jammed in but there was some casing metal kinda hanging out the side of the case - a little hard for me to explain. Anyhow... it scared the sh*t out of me! I had to remove the barrel and use my cleaning rod to push out the shell casing.

When this happened I was having fun shooting as fast as I could pull the trigger. Somehow when the firing pin slammed up against the shell the shell was not fully seated in the chamber and blew out the side. I had little black powder stuff on my face. Also, when I took out the shell I noticed that it was smaller then the Long Rifle casings that I had - almost seemed like a Long.

Strange huh?



Subject: Out Of Battery Ignition

Posted By: ML - Registered User

Posts: 224

Posted At: (1/10/02 6:24 pm)

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Out Of Battery Ignition

Mr. Roberts actually describes his episode rather well, and his terminology is likewise commendably accurate.

The correct name for this phenomenon is "firing out of battery," that is, firing before a firearm’s action is correctly closed and locked ("in battery"). As Mr. Roberts has discovered, if a cartridge ignites without being fully supported in the chamber, the cartridge case will generally burst, blowing hot gas, unburned powder, and small brass particles near the shooter’s face (a good reason to always wear high-quality shooting glasses).

I would be curious as to if the bullet ever left the cartridge case mouth, or if our shooter checked to make sure the bullet was not lodged in the barrel--both of these may be problems, and should you ever experience a burst cartridge case or out-of-battery ignition, I’d advise you to check for both.

In more powerful weapons, an out-of-battery discharge can easily ruin the firearm: with a .22 Long Rifle, there may be no damage to the weapon at all.

Now, on to the inevitable question: what caused this, and how may it be avoided? I rather doubt that the ammunition had much to do with it, although centerfire primers set too high in the case may contribute to the situation. With a .22 such as this, I suspect a dirty chamber or unburned powder and lead shavings in the breechface/magazine area. If the cartridge did not enter the chamber, or entered only partially and then stuck, it still should not discharge; however, more unburned powder or dirt in the firing-pin channel may have kept the firing pin far enough above the surface of the bolt face to effect ignition. Only close inspection of the cartridge case’s head would confirm this.

If you find no firing-pin indent, perhaps the bolt striking the rim of the case itself was enough to cause ignition. This is unusual, but the .22 Long Rifle is, after all, a RIMfire cartridge design.

I’d give your Marlin a thorough cleaning, paying particular attention to the chamber and bolt-face area. A sharp hardwood splinter or toothpick will help you dig out some of the inevitable crud. Dismantle the bolt, and thoroughly clean the firing pin and firing-pin channel in the bolt. Examine any of the fired cases (if you have them) to see if they exhibit abnormal characteristics (bulging, etc.). If you have the burst case, inspect the case head area carefully for signs (or lack thereof) of a firing-pin indent. And of course, make sure there is no bullet lodged in the barrel.

Our friend Vector posits that you might have experienced a "cook off." This situation occurs, as Vector notes, in a hot barrel. Chambering an (unfired) round in an excessively hot chamber (such as one heated by automatic firing or long, rapid semi-auto strings) can lead to the charge igniting due to the temperature soaked up by the cartridge. But I’m afraid I don’t think a cook-off is the culprit in this case, as the condition occurs with the bolt fully closed--indeed, that’s a prerequisite, like closing the door on an oven. If a cook off were the case, the rifle would have discharged (still dangerous--pay attention to Rule Number Two: "Never let the muzzle of a firearm point at anything you are not willing to destroy"), but the case would not have burst.

Adhere to the four rules, wear shooting glasses, and keep your guns clean.


Of all the things I've lost, I think I miss my mind the most.

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