The Extreme Danger
of Squibs

We all know squibs are bad. The most common result is a bullet stuck in the barrel. If the shooter is not aware of what’s happened, they might try to fire the gun again. This could result in the gun exploding and injuring or killing the shooter or bystander.

Squibs can result from having no powder in the case, too little powder, or a failure of the primer to ignite the powder. Just how dangerous a squib is depends on how far the bullet has moved. In a semi-auto pistol the bullet might not move very far and would prevent another round from being chambered. This is the best type of squib, because it renders the gun inoperable. It forces the shooter to figure out what happened and fix it.

The worst type of squib pushes the bullet far enough into the barrel it dopesn’t prevent another round from chambering. If the gun doesn’t cycle, the shooter might not realize the primer went off. Hearing protection works very well and if there are other distractions like other people firing guns, we might not know the “click” of a misfire was actually a “pop” of the primer going off. If the squib is mistaken for a misfire, the shooter might rack the slide to clear it and cycle the next round in and fire the gun. Kaboom! Guns don’t behave well when there’s an obstruction in the bore, and this is a worst-case scenario come to life. You might get lucky and just bulge the barrel or have two projectiles exit, but don’t bet your life on it — because you are.

With a revolver, the squib might result in the bullet getting stuck between the cylinder and the barrel, preventing the cylinder from turning. You should hope this is what happens, because this will force you to stop and determine the cause of the malfunction. If the bullet clears the cylinder and lodges in the barrel and you aren’t aware of what happened, kaboom again!

Extra Scary

There’s another scenario where the squib is particularly insidious. In this dastardly condition which plagues semi-auto pistols, the squib will cycle the gun and load the next round in the chamber, even though the bullet did not exit. Because the gun cycled, it gives the impression all is normal. But it isn’t. This can easily fool the shooter into not knowing anything is amiss and will pull the trigger again. You know the story now — kaboom.

But is that possible? Can the gun cycle if the bullet doesn’t leave the barrel? I had been under the impression the bullet had to exit in order for there to be enough reciprocal rearward force to make the slide move far enough back to cycle the gun. I don’t know why I thought that, but I did. And I was wrong.

I was working on low recoil loads for the .380 Auto. I perused various load manuals for the lightest loads and checked out a normally reliable website and their .380 data for a 115 grain JHP bullet. Their lightest load was 1.6 grains of HP-38, producing 520 fps from a 2.25″ Colt Mk. IV barrel. This is one of the lightest loads I found anywhere.

I wanted the light load for my semi-auto pistols. My principle concern was they wouldn’t have a strong enough recoil impulse to cycle the slide. I fired them in a Zenith Girsan MC14, which is patterned after a Beretta 84 Cheetah, but with an enclosed slide instead of the open slide of the Beretta. The MC14 barrel is 3.82″ long.

The first shot didn’t go well. I got a blast of hot gas in the face. I thought it meant a pierced primer or case blowout, the latter being unlikely given the low charge weight and pressure. I cleared the gun to assess what happened. I want to emphasize the slide cycled and loaded the next round in the chamber.

I was very glad I stopped and cleared the gun. What I did not know at that moment was the bullet was stuck in the barrel. If I had ignored the blast of gas and fired the next round, nothing good would have happened.

As I did a quick inspection, I happened to notice the bullet was protruding about half the way out of the barrel. I’m glad it was protruding because it was not my first instinct to look down the barrel to see if the bullet had exited. I was still in the “pierced primer” mindset. I located the fired case and it was intact and the primer was not pierced.

Talk about a teaching moment. I learned the bullet does not need to exit the barrel to generate enough force to cycle the slide.

Experimenting

I turned this into an experiment and loaded some rounds with less powder and some with no powder. With 1.0 grain of HP-38, the Nosler bullet moved 1.38″ down the barrel. The slide cycled normally; the spent brass was ejected and a live round was loaded in the chamber. The slide also cycled and loaded another round when using only half (0.5) a grain of HP-38. It didn’t take much powder to cycle the slide.

Powered with just a primer, the Nosler bullet moved 0.36″. The slide moved only slightly, not enough to eject the spent brass or load another round in the chamber. I tried this with a CCI 500 (standard) and 550 (magnum) primer. The results were the same.

I also tested this in a 9mm Glock 19C, with a non-ported barrel, so it can be thought of as a regular G19 with a slightly lighter slide. I used Nosler 115 grain bullets and HP-38 again. The results were a little different than with the MC14.

With the Glock, bullets were stuck in the barrel with up to 1.5 grains of HP-38, just like with the .380 Auto MC14. However, the Glock never cycled, not even with charges of up to 3.0 grains of powder.

When testing the Glock, the rounds resulting in a stuck bullet made a “pop” sound, but when the bullet exited, it made a “bang” sound just like normal. The Glock did not cycle in any of these instances of low charge weights, so it requires you to rack the slide to make the gun ready to fire again. Hopefully, the difference in sound will be enough of a warning the shooter needs to stop and evaluate the gun and the ammo.

Why did light loads cycle the MC14 slide but not the Glock? I can’t say definitively, but I suspect it’s related to how they operate and the weight of the moving parts.

The Zenith MC14 is a blowback pistol and the Glock is a locked breech pistol. With blowback pistols, the barrel does not move during recoil, only the slide. With locked breech pistols, the barrel and slide move together during recoil. The barrel only travels a short distance during which it unlocks from the slide, after which the slide alone travels rearward the remaining distance.

The MC14 slide weighs 8.70 ounces. The Glock 19C slide weighs 12.15 ounces, and adding the barrel weight comes to 15.75 ounces. The Glock slide/barrel assembly is close to twice the weight of the MC14,

Don’t Misinterpret

This example demonstrates how undercharged loads can easily lead to damaged guns and injuries. It’s possible to misinterpret a squib as a misfire or a successfully fired round if the gun appears to function normally. Also, many of us shoot fast, whether it’s for fun, training or competition. Split times between shots is measured by fractions of a second. If a squib gets far enough down the barrel to allow a revolver’s cylinder to turn or cycles the slide on a semi-auto pistol, and we don’t notice it or are too far into the trigger pull to stop, that’s when your fun day at the range turns into a very bad day.

In all my decades of shooting, this was the one time when getting a blast of hot gas in the face was a good thing. It was a warning something bad would happen if I pulled the trigger again. The gas escaped because the undercharged load was not generating enough pressure to expand the brass enough to seal the chamber like it does with a normal powered load.

Handloaders need to take special care to ensure their light loads will operate safely in their guns. The usual advice of not going below published load data has new meaning for me. Even some published low power loads might not be appropriate.

It serves as a stark reminder we have to be extra vigilant when testing low pressure/low velocity loads. The danger of a stuck bullet is real. The reality we might not be aware of a stuck bullet is also very real. I feel fortunate the bullet was protruding from the barrel because I might not have seen it if it was deeper. I wasn’t looking for a stuck bullet, because that thought hadn’t entered my mind at the time. I got lucky. Very lucky.

I was surprised how little powder was required to cycle the slide of the MC14. Just one-half grain of HP-38 produced enough energy to eject the fired case and load another round. The bullet traveled less than an inch down the barrel, but this made plenty of room for the next round to fully chamber and be ready to fire again.

The bullet only needs to move far enough down the barrel to allow the next round to chamber. With my examples, a primer alone did not move the bullet far enough. Yet the bullet was stuck firmly in the rifling. It took a squib rod and some whacks with a hammer to remove it. How far the bullet moves might depend on the length of your barrel’s throat, and the weight, length, shape, bearing surface and hardness of the bullet. Any difference in these features can allow the bullet to move far enough to make room for another round to fit in the chamber.

I’ve demonstrated it’s surprisingly easy for some pistols to cycle even when the bullet is stuck in the barrel. These are the evilest types of squibs because the shooter might not be aware of what has happened and try to fire another round. I hope this illustrates how easily something can go wrong and reminds people to be wary if something appears out of place when you shoot, stop immediately and check the weapon.

You might be saving yourself from a really bad day.