JAM!

Guns Magazine, April, 2000 by Charles E. Petty

When analyzed properly, gun stoppages can provide you with a great deal of information about the condition of your firearm.

There is nothing more frustrating than a gun malfunction. Malfunctions can have serious consequences if the gun happens to be a duty or defensive piece. Unless a gunsmith can see what's going on or is given a detailed description, it is impossible to diagnose with certainty why something went wrong.

There was a time when malfunctions were a way of life when shooting a pistol, but over the years manufacturers have improved their products to the point that it's really unusual to have much trouble with new guns today. Yet sometimes gremlins come along or sometimes something needs fixing.

It's All In The Elbow

I don't know if we could ever establish with certainty the most prevalent cause of malfunctions, but shooter error and faulty magazines would probably emerge as the number one and two suspects. We have to remember that automatic pistols are reciprocating mechanisms that depend on the movement of one part -- the slide -- while the other part -- the frame -- stays still. If the shooter lets the frame move too much, the energy of the cartridge will be partially absorbed and a malfunction is possible. This situation is commonly called "limp-wristing."

Sometimes the only thing necessary to cure this problem is to lock one's elbow. A typical limp-wrist stoppage occurs when the fired case is trapped between the slide and barrel in the "stovepipe" position -- with the case mouth pointing straight up.

If shooter-induced problems are the cause, then magazine troubles aren't far behind. Even though a magazine looks like a very simple piece of gear it has to perform some complex tasks at precise times in the pistol's cycle.

Let's look at magazine function. It has to present a fresh cartridge in the right place and at the right time to be pushed forward by the slide as it closes at the end of the firing cycle. If the round doesn't get there in time, the slide will close on an empty chamber and you'll get click instead of bang. If the round gets there too soon it can interfere with the ejection of the fired case.

Magazine-related malfunctions seem to happen most often with either the first or last round. Both of these malfunctions are almost always spring-related. High-capacity magazines are especially prone to this problem.

The magazine spring actually has quite a bit of work to do for it has to lift a stack of cartridges, which can be significantly weighty. A typical high-capacity magazine load of 9mm, .40 S&W or .45 ACP cartridges weighs nearly half a pound.

If the magazine spring is too strong you'll get a failure in which the first round is tipped nose down into the feed ramp. The reason is that the spring prevents the round from stripping freely from the magazine as the slide tries to close.

At the other end of the spectrum a magazine spring that's too weak will often result in the last round being trapped with the nose pointing straight up because the cartridge isn't lifted fast enough to be picked up.

Game, Set And Match

While we're talking about magazines we need to deal with another problem that is far more theoretical than real. Popular wisdom says that springs in magazines that are left loaded will "take a set" and fail. As with anything that has some basis in reality, this is a potential problem that really doesn't happen very much, but which gets an inordinate amount of concern and generates huge quantities of angst.

The wisdom creates the perception that on any given day, at any given time, your magazine will suddenly quit working. Some people routinely replace magazine springs, but a much better idea would simply be to use the ones you've got. Personal defense weapons should be shot regularly since emptying the magazine allows the spring to "relax" and takes care of potential problems. I'm not much for working on guns to take care of something that may never happen, but I am a big believer in shooting regularly.

Clean And Polish

Being dirty doesn't normally cause a gun that works well when clean to stop working. Some possible scenarios, such as big accumulations of unburned powder or bullet lube, could make a gun choke, however. Those are easy to rule out -- and should be -- before you spend any money on parts or services.

Shooters will often attempt to correct a malfunction problem by "polishing the feed ramp." This is not the panacea some would like us to believe -- especially those who charge a lot of money for doing it.

If you study the geometry of how the cartridge exits the magazine and enters the chamber, you'll see that it either doesn't touch the ramp at all, or skips across it only briefly. Now it is surely true that the feed ramp should be smooth, but if the cartridge barely touches it in the first place, what good will polishing it to mirror brightness do?

There are two places where a little judicious polishing may solve a problem, however. If the area where the barrel transitions from the feed ramp to the chamber is rough, it can catch the case mouth or cause the round to drag and slow down enough to cause a stoppage.