45. cal. eye catcher

[tr4252]

Al,

This is one of the strangest accidents I've ever heard; if it hadn't happened to my father, I'd be very skeptical.

He's been shooting for a long time, reloads, has a lot of different guns; knows a thing or two about firearms. So when he told me what happened with this 20 or so year old Argentine made 1911 .45, I knew that if he couldn't figure it out, I wouldn't have a clue.

What happened is that an unfired round somehow exited the gun as he fired it, sheared off the rear sight, and hit him in the right eye. He was wearing shooting glasses, and wasn't hurt too much. No dimple in the primer, so it hadn't been struck by the firing pin. I realize you might need more information; that's all I have at the moment, except that the company which made the sight sent him a free new one. My opinion was that he should permanently retire the son of a bitch.

Have you ever heard of anything like that? I never did. Didn't think it was possible, exactly. Any ideas?

Tom

[Vagrant]

I once read about a .45 Single Action Army that went "full-auto"
Not a bad trick for a single action revolver. This is almost as confusing
There's [almost] always an answer

[natcherly]

I usually ascribe such inexplicable events to Spontaneous Human Combustion.

[JAGMAN]

Sounds like the mag feed lips were not holding tension on the round and when the slide went rearward the pressure from the mag spring forced the bullet up and out. The reason it went backward could be that the round came into contact with the slide on it's way up and was thrown backwards. That would be my guess with the info you provided. I would examine the feed lips and the diameter of the round in question.
Jagman

[Vagrant]

Since it happened as he fired, the fired round probably influenced the unfired one to behave the way it did. That fits right in with Jagman's explanation. We just add the fired round providing the rearward force. I would have expected one of them to fail to eject since the ejection port is pretty tight for both rounds to make it out but the unusual is exactly that, not what we expect.

[Vagrant]

NOW explain the SAA, [Peacemaker, Model P, Equaliser] that went "full-auto" Answer later if no-one gets it right. This was a "one in a million" case of THREE things going wrong at once. Two were the real cause and one just made it a sure thing. A SAA that dumps all 6 every time you pull the trigger is an adventure, I'm sure

[JAGMAN]

Get your Dad a new mag. TR. was it the next to last round???
Found this tidbit - on a Colt forum.

Inertia! Just no way to get around Newton's Laws regarding motion.
Remember the old trick of jerking a tablecloth out from under a table setting? This is the principle at work here.

We have a round in the chamber and one round in the magazine.

Bang! The slide starts to move as the pistol torques up and back. The slide holds the last round slightly below the feeding position until it moves far enough to uncover it. Just as the magazine spring is struggling to move the round into position, the round is in a sort of "Limbo" while the pistol continues to move backward in recoil. The round obeys Newton, and stands still while the gun is moving away from it.

The magazine spring catches up, and gets the round up and into the underside of the feed lips, but because the pistol pulled backward away from it (Even though the pressure from the slide drags the round backward in the magazine)...it settles down forward of the feeding position. At this point, if the magazine spring is strong enough to keep it there, the slide pushes it ahead of the extractor. The pistol either fails to go to battery with the round fully chambered, and the front of the extractor rammed against the back of the rim. Extractor breakage is an eventuality.

If the spring isn't strong enough, the round is forward of optimum feeding position just as the slide smacks the impact surface in the frame, and triggers a second recoil impulse. The gun makes a short, hard jerk upward and backward...and the round is in limbo once more because the mass of the round has caused the magazine spring to compress slightly. The round...already too far forward in the magazine...jumps the follower, and is free of the magazine. The follower pushes the slidestop up as the slide moves forward, and the slide locks. If the magazine spring is weak enough, the next to last round will be ejected from the magazine, and the last round feeds. Ever found live ammo among your brass? Heeere's yer sign!

The problem is two-fold. One is the spring that has fewer coils to make room for the extra round. There is ample tension to feed until it gets to the last round...and tension is at a mimimum...but sometimes it can happen before the last round. Upping the spring rate helps, but doesn't address the other issue.

The other part of the problem is the smooth follower. Browning knew how
inertia would affect things, and he put a small dimple on the top of the magazine follower. The dimple's function is two-fold. It adds a small amount of height to the follower in order to give it a "Leg Up"...and it stops the forward movement of the round. More accurately, it keeps the pistol from moving out from under the round in recoil. In this function, it's basically a back-up for the spring as it fatigues, and provides a better opportunity for the round to stay in position to be stripped from the magazine by the slide instead of being pushed ahead of it...or... in the extreme cases, escaping from the magazine completely.

John Moses designed a 7-round magazine and he put a dimple on the follower for very good reasons. Whenever we try to change things in order to "improve" the gun...we very often cause problems. There just ain't no such thing as a free lunch, I'm 'fraid.

[Sam Hotton]

Good morning Mr. Vagrant,
Sounds like that model P had a lot of cylinder gap and end shake, probably had a weak mainspring and a light sear. The old Model P thought it was a Fosberry and as it fired the cylinder recoiled backwards cocking the hammer against the weak mainspring and kept running as the trigger was held back.
Close?

All the best Al,
Sam H

[sonnyboy]

Have you ever heard of anything like that?

I've owned several Colts/Colt clones, and never experienced this...but I have had a S&W Model 46 do something similar...I had loaded two .22's in the mag, fired one, and when I looked, the slide was locked back [indication mag & chamber empty]...It *was* empty...no 2nd round...couldn't find the 2nd casing anywhere either...maybe it fired, maybe not...it just disappeared...

Over the years, I have experienced "run-on" or whatever multiple discharges are called...On a big slow-firing weapon like a .45, you can usually hear each distinct discharge...on a smaller round, it's almost impossible to separate the sounds...

I had an old Hi-Standard Dura-Matic with a sticking firing pin that would fire the whole mag like a burp gun and sound like one long echoing shot...

[Diggaway]

Jagman's analysis sounds good to me re Tom's conundrum but Vagrant's model P example has me puzzled. Assuming that each chamber was more or less in line with the barrel at discharge some condition had to retract the hammer back far enough to rotate the cylinder and pop the primer. I can't see the cylinder moving sharply enough to accomplish this but a pierced primer just might do it especially if in combination with a hot handload. The trigger was either held back or sheared its tip, the firing pin was too sharp and as Sam mentioned, the mainspring may have been a bit weak. Close?

The old Model P thought it was a Fosberry

Regards, Diggaway

[Vagrant]

The "Full-Auto" SAA
[cylinder was tight, no end-play, if it hadn't been the gun could have fired "off index" and suffered "catastrophic failure" which can REALLY hurt]
In increasing importance:
1 - very light trigger [a maybe/maybe not, factor]
2 - worn/eroded firing pin bushing
3 - Chipped firing pin
It went like this :
1 - On firing the chipped firing pin pierced the primer causing a backflow of gas.
2 - The worn/eroded firing pin bushing allowed enough gas to hit the hammer face cocking the hammer and indexing the cylinder.
3 - The light trigger ensured that the trigger was not released [or failed to "catch"] before the process repeated and repeated and repeated and repeated and repeated. [a HEAVY trigger might have been "held back" so firmly that releasing in time was unlikely].
Direct "gas impingement" a few decades before it was used on the M-16 {Sooner or later the firing pin, bushing, and hammer parts would probably have headed eyeward turning a "boomer" into a "bummer" }