I saw a rifle go full auto today
 

I was at a Missouri dept of Conservation shooting range today. I like it because it covered -Shade and Rain and cheap $3 an hour.

Anyway I was walking behind the shooters and watching a woman shoot a MOSS French rifle. Then all of a sudden three casings and one startled lady.

The range has rules of three seconds so I know she didn't mean to.

Questions for Gun enthusiast, What makes a rifle just go full auto? Is a Moss rifle prone to this?

E-A

Re: I saw a rifle go full auto today
 

Slam fire, or bump-fire.

http://en.wikipedia.org/wiki/Slamfire
http://en.wikipedia.org/wiki/Bump_fire

I don't know anything about Moss rifles though, obviously it was a semi-auto type.

Re: I saw a rifle go full auto today
 

or Maybe a problem with the sear.

Re: I saw a rifle go full auto today
 

Slam fire?

Never heard of it before. I was talking with the very sheepish looking couple and they said it was due to ammunition. I didn't believe that. But maybe Slam fire can be triggered from hot ammunition.

E-A

Re: I saw a rifle go full auto today
 

I don't believe it either -

Possibly, hot ammo and weak firing pin spring

or maybe dirty firing pin hole causing the pin to hang and protrude and firing when the round chambers, etc.

No way it should be due solely to ammunition - some other malfunction is occuring at the same time

Re: I saw a rifle go full auto today
 

Could be the wrong-sized ammo? lol!

Could also be primers, poorly sized brass or projectiles that aren't seated properly, the firing pin actually can contact the primer on the return stroke, but usually not with enough force to initiate the primer. Slam fire condition could do it, but yeah ammo that is way out of spec can also encourage it. Wrong powder load could make a gun do something strange like that, that's the least of your worries though, the barrel failing might be worse.

If it was the wrong ammo or an ammo problem, they were very lucky indeed, as the gun was probably shooting out of battery. If he's a reloader, he should quit while he's ahead. Maybe it's a good object lesson to test new reloads with just two in the clip to prevent it turning into a machine gun if something goes wrong.

Would have been pretty funny to see (once the gun stopped firing, and all the fuss died down that is). hehe.

Re: I saw a rifle go full auto today
 

It's MAS. I don't know if they're more prone to this than others. I have heard of this happening in the SKS.

While the actual mechanical cause can vary, in the end the "trigger" is the same: the firing pin does not retract into the breech face like it should. Maybe the firing pin broke, or if it's a 2-piece pin and a spring is broken. Or it's a "new" milsurp, and not all the cosmolene was removed, and the pin is stuck. So after the brass on the previous round has ejected, the slide comes forward, a new round is stripped off the magazine and shoved into the chamber, and the firing pin is sticking out! Hopefully the action is completely closed... :eek_ma:

Unlike deliberate full auto there's no way to stop it--either the pin retracts or you exhaust your ammo. The only thing to do is to keep the damn thing pointed downrange and pray.

Re: I saw a rifle go full auto today
 

Since we're talking about shooting....this is a pretty cool clip:

http://www.youtube.com/watch?v=lxqgO...elated&search=

Re: I saw a rifle go full auto today
 

Commercial 7.5 x 54mm ammo made for French rifles by other countries (I mean, not by France) is notorious for having sensitive primers that can lead to burst fire. You said 3 casings? I suspect that might have been her problem. She can replace the original steel firing pin with a lighter pin, and it should resolve the problem, or at least reduce the chance of it happening again.

Re: I saw a rifle go full auto today
 

Even a properly maintained firing pin can slam-fire in an SKS if the primers are soft enough. Just the momentum of the free floating firing pin is enough to activate the primer.

Re: I saw a rifle go full auto today
 

Pretty easy to get some semi-auto mil rifles to double, just have a light grip on the rifle and don't follow through on your trigger pull. The bolt carry forward inertia resets the mechanism and your trigger finger is still holding right at the sear release point; so the gun fires again.

Somebody with slow reactions might have two doubles in a half second or so before they grab that rifle with all they have, and hold that trigger fully to the rear. Pretty damn unnerving. Had this happen while shooting my M1a once. Benchrest techniques of minimal stock handling and trigger release are not advisable, for this reason, with some semi-autos.

When a semi-auto goes full auto it will dump its entire magazine load due to a sear failure. A slam fire occurs when the round fires before battery lockup is complete and can kill injur the shooter while destroying the weapon.

There should be a discussion of doubling and slam fires on Fulton Armory's homepage for those who want a better explanation.

Re: I saw a rifle go full auto today
 

Somone gave my grandfather an old 22 once that he fixd up and it somehow got stuck to full auto. Admittedly it was fun, but very dangerous until he got it fixed. Once you squeezed the trigger, it would unload the clip, like it or not. There was no way to stop it.

Re: I saw a rifle go full auto today
 

A "slam fire" causes catostrophic failures. I doubt if it was a slam fire.

More than likely, the hammer was following the bolt closed, which is probably a problem with the trigger group, as previously stated.

Could have been the "bump fire", or just a bad hold. I know some guys who can bump fire from the shoulder. Watching them, you would swear they were firing full auto guns.

Re: I saw a rifle go full auto today
 

Most full-auto only guns are designed with a "pin" permanently protruding from the bolt face - i.e. slam fire (fires from "open bolt" vs. "closed bolt"). Now, if the gun wasn't meant to work that way you might blow it up. Especially if bites too much primer while loading the live round.

Re: I saw a rifle go full auto today
 

No, they're not.

Some Machine Guns (not the semi auto or automatic rifles about which we are speaking) fire from an open bolt.

Anyway, a slam fire is caused by a cartridge firing out of battery. Do that in a MAS and you're going to have pieces of rifle, if not pieces of shooter.

BTW, those MASs are nice looking...never fired, dropped once.

Re: I saw a rifle go full auto today
 

Damn, you stole my joke. :)

The French don't actually fight with their weaponry anyway, they just deal in it.