It is my understanding that 1911s, Glocks, etc. are called “semi-automatic” because “the gun fires upon each trigger pull.” The same definition is also used with rifles and shotguns that fire upon each trigger pull.
But, um, doesn’t a revolver also fire upon each trigger pull? Why aren’t revolvers also called “semi-automatic”? Or does the term also require the gun to have an auto-loading mechanism? And if that’s true, why doesn’t a revolving cylinder constitute an auto-loading mechanism?
I may be wrong, but I think that because you have to cock a revolver before each shot, it’s not semi-automatic.
FYI, I’ve never even touched a handgun, that’s just an educated guess…
hrh
I think that’s only true with “single action only” revlovers.
Semi-automatic automatically chambers the next round and cocks the hammer but doesn’t continue firing the next round like an automatic. It requires another pull of the trigger.
Revolver revolves the next round into position for firing but it does not cock the hammer.
A modern “double-action” revolver will fire a new round with a simple pull of the trigger. This is because pulling the trigger rotates the cylinder, cocks the hammer, and releases the hammer, firing the gun.
However, it wouldn’t make sense to call this sort of double-action firing semi-automatic because you are still cocking the hammer manually - by pulling the trigger. And you do have to pull reasonably hard on the trigger to cock the hammer.
I believe that they make semi-auto pistols that are double-action only. In other words, each shot requires you to cock the hammer by pulling the trigger. So perhaps it’s a matter of semantics.
Semi-automatic: A self-loading firearm, which ejects the spent shell upon firing, inserts another loaded cartridge into the chamber, and locks the bolt, readying the firearm for another shot. This type of firearm will fire once for each pull of the trigger, but the trigger must be pulled for each shot.
The 4 main functions of a semi-auto are Feed, Fire, Extract, Eject. With the exception of fire, revolvers do none of that. (feed meaning feeding from a removable magazine). A semi auto extracts the used shell casing (hence the automatic part) where a revolver has to have them manually unloaded.
Woo boy, I bet this thread will be a cantidate for Great Debates before it’s over with. I will regurgitate what I learned in my firearms training:
Semi-automatic means “Ejecting a shell and loading the next round of ammunition automatically, but requiring a squeeze of the trigger for each shot.”. So you see, it takes more than just one shot per trigger pull to make it a semi-automatic, it requires autoloading capability as well. A revolver doesn’t automatically reload it’s chamber for every shot, instead it has six seperate chambers that you must manually load. An autoloader only has one, that the mechanism reloads from a magazine or clip.
And on preview, I see pkbites has beat me to it, but I am gonna hit submit anyways. 
Doesn’t necessarily have to be a removable magazine. The SKS, for one, fires from a fixed magazine, but is still semi-auto.
Darn it Cool!
I had just thought of that right after I submited my post, but hoped that nobody would think of that!
I should have remembered about the SKS and the like. I own one and have sold quite a few!I’ve never fired mine though.
sigh I’m late again.
What pkbites, Joey G and Joe_Cool said.
…are called “semi-automatic” because “the gun fires upon each trigger pull.”
This statement is the problem.
First of all, every gun fires upon each trigger pull. We all know the intent was to say it fires only once per pull, but if you’re going to call a statement a “definition” it’s got to be correct in all pertinent details.
Secondly, the firing/trigger pull relationship is significant only in differentiating between (full) automatics, which continue firing so long as the trigger is held, and semi-automatics, which require a separate trigger pull for each shot. The trigger pull aspect, in and of itself, is not used to define types of gun–it doesn’t yield unambiguous clarity. It’s used to describe certain guns’ functions.
The distinction is largely what causes the next round to come into firing position. If YOU have to supply the mechanical energy, it’s not automatic. If some of the explosion of the previous bullet has been directed to bring the next round into play, the weapon is (semi-)automatic.
Whoa, there, Kemo Sabe! That just ain’t true! There are guns a’plenty that require manually operating the action before pulling the trigger will fire another shot. Here I’m thinking of rifles and shotguns that belong to the lever action, pump action, and bolt action families (hinge action, you can get two shots off before you have to manually work the action).
Handguns, they’re a different story. But you just said “guns,” and what kind of friend would I be if I didn’t nitpick?
You gotta be kidding. The SKS is the “civilian AK-47” right? You’re telling me it uses a fixed magazine? I always thought they used a standard detachable mag like all the other semi-autos I know of. I’m sure I’ve seen SKS’s at gun shows with the usual detachable banana mag. Help me out here.
As for the original question. I think it is historical semantics. When the first “automatic” (really semi-auto) pistols came out in the 1890s there were still many single-action revolvers. You had to cock the gun manually with each shot. The trigger pull only fired the cartridge. You may have seen this in western movies where the gunslingers are rapidly whacking the back of the gun with one hand while firing with the other. This “whacking” action is simply repeated cocking of the gun after each shot. The semi-auto pistol was really quite “automatic” indeed compared to all the bother you went through to shoot repeatedly with a single action revolver. Modern revolvers are essentially all double action. The trigger does everything including cocking the hammer, advancing the chamber and firing the round. The only thing you do is load.
oops. I should have mentioned that it is possible to take off the fixed magazine on an SKS and add a detatchable mag. But doing so may be illegal in some areas. Also, many SKS won’t accept an AK mag, and SKS banana clips are not as available as AK mags.
However, a good SKS rifle usually costs much less than even a cheaply made AK.
I second this answer. That is truly the key. The difference is this: After you pull the trigger on a semi-auto, the gun automatically cycles its action and loads a new round ready for firing. With a revolver, after you pull the trigger the empty casing remains under the firing pin, and the gun has not cycled a new bullet into firing position.
So a Vulcan Cannon (Gattling Gun) is not an automatic? < veg >
As always, we have to throw in the exception to have some fun!
The Mateba line of revolvers uses the recoil energy of the fired round to cycle the cylinder. (This revolver has a ‘slide’ with the cylinder mounted ‘upside down’, so the rounds feed from the bottom of the cylinder, not the top.)
I’ll go back to playing with my 629 now
Hm. Never thought of that. Technically it isn’t an “automatic” since it’s electrically powered. But legally it can be classed as a “machine gun” (ignoring that it actually falls under another category – whose name escapes me now – “destructive device”?) because it can fire multiple rounds for each pull of the trigger.