[speeder]

I always thought that guns jamming was for things getting stuck in the barrel or failing to fire.

After watching this site I noticed that jam is... mechanical issues, SPECIALLY with the slide, on this weapon, I believed this weapon had a special semi-auto mechanism, that is, that something ensured the slide would slide back, after seeing it slides back purely from recoil I concluded two things:

One, it is a hell of a recoil... (otherwise the slide would not slide back).

Two, it only works if you don't let the gun go backwards, if you shoot, and allow it to go back, the energy of the recoil will be spent by your body, not the slide, thus the slide won't slide, thus you will have to slide manually... Making it very non-semi-auto.

Also I noticed the ejector also rely on some small machined parts (like the one that hold the cartridge rim), and thus if not made properly will probably fail (the slide will go back but the cartridge won't go back with it, this probably would be the sort of jam that is an actual jam, you would need to push the cartridge out with another object).

And the amount of springs I am seeing around, mean cyclic fatigue failure of the metal probably causes a couple of issues, I think that a frequently fired gun probably more than cleaning also might require frequent change of springs.

[exelius]

All of these are concerns, to be sure.

There is a reason cartridges are made of brass: it's hard, but it's softer than the steel that the gun is made of. So wear and tear on the ejector mechanism is lessened. Same with the bullet, which is a softer metal than the barrel.

And yes, the .45 specifically has a hell of a recoil, though the weight of the slide has a lot to do with it as well. Just remember your basic physics: if you're ejecting a 20g projectile at 1200fps, the 600g slide is going to travel backwards at 40 fps (which is still very fast).

Cyclic fatigue is also a thing; which is why you make sure to keep your springs lubricated and replace them periodically. A gun is a machine that must be maintained properly, like any other.

[Zancarius]

> And yes, the .45 specifically has a hell of a recoil, though the weight of the slide has a lot to do with it as well. Just remember your basic physics: if you're ejecting a 20g projectile at 1200fps, the 600g slide is going to travel backwards at 40 fps (which is still very fast).

The 1911 I believe was designed around a ~230 grain projectile (15 grams) that fired at about 850ft/s. There are some 185gr. rounds on the market today that do advertise the 1150-ish ft/s. velocity, but I find in practice that the feel isn't markedly different.

Along those lines, it's important to note that "felt recoil" is perceived somewhat differently to different people (grip strength, hand size, body type), and some people are simply more sensitive to recoil than others. Case in point: I don't find the 1911's recoil to be particularly notable; some think it kicks like a mule. If you're firing heavier projectiles, it'll feel like more of a push than a snap, but it's definitely not unpleasant (the impulse of the recoil is just as important). The 185gr. rounds tend to be a bit snappier (shorter, faster recoil), but still manageable. I'd classify "hell of a recoil" as anything from .44 magnum on up, and there's plenty of large, really ugly calibers out there that are probably very unpleasant to shoot (500S&W comes to mind). The .45ACP is definitely not one unless you're shooting it from a much smaller gun.

Since we're on the topic of felt recoil and considering it is also a function of the weight of the gun, I'd much rather shoot a 1911 than some of the tiny .380 autos on the market like the Ruger LCP [1]. If it's unpleasant to shoot, you're not as likely to practice with it. Even the smaller calibers can hurt if the gun is light enough. :)

[1] http://www.ruger.com/products/lcp/models.html

[exelius]

You're right about my numbers being off - I was killing time on a long flight and it's been a while since I've shot a .45 (mostly because I have small hands.) But the general principle remains: the slide shoots backwards with equal force to the projectile.

And yeah, any sort of magnum cartridge (.357, .44, .50) is a beast because it has double the powder load. The .50 S&W in particular, as you mentioned, has so much recoil that it's prone to double-firing (S&W even recommends that you only load 1 round at a time). But among standard handgun cartridges, I still think the .45 kicks a lot more than say, a 9mm. It's also just big enough that you can't really stagger the rounds in a magazine without making it super-wide; hence why a standard 1911 holds 8 (7+1) rounds and 9mm pistols of the same weight can hold 15+. I find a modern .45 like the USP (12 rounds) to be uncomfortably wide for me to hold; though a Glock 17 (9mm, 17 round mag) is fine. That definitely makes the recoil feel worse.

[Zancarius]

> You're right about my numbers being off - I was killing time on a long flight and it's been a while since I've shot a .45 (mostly because I have small hands.) But the general principle remains: the slide shoots backwards with equal force to the projectile.

Eh, it doesn't really matter, IMO!

Realistically, no matter what the math might say, felt recoil is still a subjective spectrum (within reason, obviously too much force is going to hurt), because two people can fire the same gun and have different reactions.

Although, you definitely wouldn't catch me with a .500S&W ;) There comes a point when it's too much gun to be enjoyable.

My father had a .454 Casull once. He sold it because he could only go through a couple cylinders before a blister would wear on his hand through gloves. I've since borrowed his philosophy: If a gun hurts a bit too much to be fun, there's no point owning it!

[mrbill]

I actually bought my first 1911 yesterday - a Ruger SR1911 Commander. Put 60 rounds through it at the range to break it in, and my wrist was none the worse for wear.

If I'd put that same amount of ammo through my Glock 17, I would have had a sore wrist at least for a little while. I find the 9mm to be more of a "kick" while the 45 is a "shove".

The construction of the gun is going to make a difference as well - the Glock is mostly polymer with a metal slide, slide rails, barrel, and some other internal parts (mag liner, etc) while the 1911 is mostly steel.

Google says the SR1911CMD is 36.4oz, while the Glock 19 is 23.65oz, unloaded.

[chroma]

Your general point about the slide recoil is correct, but your comparison isn't. Kinetic energy is proportional to the square of velocity. k = 1/2 * mv^2

In your example, the projectile has...

    1/2 * 20g * (365 m/s)^2 = 1330 joules

...of kinetic energy. But your slide has...

    1/2 * 600g * (12.2 m/s)^2 = 44 joules

...of kinetic energy. Solve for the slide velocity...

    1/2 * 0.600kg * (x m/s)^2 = 1330 joules
          0.300kg * (x m/s)^2 = 1330 joules
                    (x m/s)^2 = 4433 m^2/s^2
                            x = 66.58 m/s

So the slide is initially traveling backwards at around 65 meters per second. Probably faster, since only a fraction of the deflagration is transferred to the bullet.

Another nitpick: I think your example is not representative. A 20 gram bullet and 600 gram slide are both very heavy for a handgun. Using typical numbers: Hydra-shok 9mm +P has a bullet weighing 8 grams, which exits the muzzle at 350 meters per second. That gives 490 joules of kinetic energy. I weighed the slide on my Sig Sauer P239 at 300 grams. Plug those numbers in, and you get a slide traveling backwards at 57 meters per second. Not too different, but worth mentioning.

That said, I completely agree with everything else in your comment. Thank you for explaining the intricacies of handgun and ammunition metallurgy.

[icegreentea]

Parent was invoking conservation of linear momentum not an energy balance. There's no requirement that both the bullet and slide have the same kinetic energy, only that the sum of energy between the two bodies remains constant.

[Zak]

I always thought that guns jamming was for things getting stuck in the barrel or failing to fire.

Those malfunctions are referred to as a "bore obstruction" and a "misfire" respectively. A bore obstruction during firing is very dangerous, as it results in the chamber pressure exceeding design limits, which may cause a catastrophic failure of the weapon. Misfires are usually due to defective ammunition or a failure to hit the primer hard enough (hammer or striker spring too weak, firing pin too short or the chamber or ammunition having incorrect dimensions).

One, it is a hell of a recoil

Almost all semi-automatic handguns are recoil-operated, including .22 rimfires, which are known for having almost no recoil. Generating enough force to cycle the action is not at all difficult; the major difficulty in handgun design was actually the converse: keeping the action from cycling too quickly. Using a heavier slide and stiffer spring is one option, but it becomes unattractive with anything but low-powered cartridges. Most pistols designed for police, military and self defense, using medium-power cartridges like 9mm and .45 auto use a locked breech action like the 1911 shown here. It and its prototypes were the first to use the tilting barrel mechanism which is found on most pistols today.

The alternative to recoil operation is gas operation, in which a port in the barrel diverts some of the propellant gasses to push on a piston to operate the mechanism. It is common for rifles, which typically use more powerful, higher-pressure ammunition than pistols, but rarely found on pistols. The Desert Eagle is a notable exception.

The .45's recoil is not generally considered severe. Most people find it milder than the .40 S&W cartridge used by the majority of US police today, itself developed as a milder-recoiling version of the 10mm auto cartridge.

Two, it only works if you don't let the gun go backwards, if you shoot, and allow it to go back, the energy of the recoil will be spent by your body, not the slide, thus the slide won't slide, thus you will have to slide manually... Making it very non-semi-auto.

Failing to hold the gun firmly is known as "limp-wristing" and does increase the chances of a malfunction. Most modern pistols will still cycle in spite of it, but the chances of malfunction are increased. Inertia usually provides enough counter force for the recoil to push against.

Also I noticed the ejector also rely on some small machined parts (like the one that hold the cartridge rim), and thus if not made properly will probably fail (the slide will go back but the cartridge won't go back with it, this probably would be the sort of jam that is an actual jam, you would need to push the cartridge out with another object).

This is called a failure to extract. It's a common cause of malfunctions. Most newer pistol designs, including many revised 1911s used a much larger extractor that protrudes from the side of the slide.

And the amount of springs I am seeing around, mean cyclic fatigue failure of the metal probably causes a couple of issues, I think that a frequently fired gun probably more than cleaning also might require frequent change of springs.

Correct. Replacement of the recoil spring every few thousand rounds is a good idea to reduce fatigue on other parts. As the spring weakens, the forces experienced by other parts are increased. This is more of a problem in some designs than others. The Beretta 92/M9 used by the US military, for example uses a tilting locking block instead of a tilting barrel, and the locking block is prone to fail if the spring is not replaced on schedule. Most pistols are less prone to this category of failure, and some would consider it a design flaw of the Beretta.