PUBLIC SERVICE ANNOUNCEMENT: A word of warning about 1911's going full auto

[snakeman21]

I thought I would post this and hopefully save someone from a bad accident.

I brought my 1911 and my AK to a friend's house the other day to shoot. He, like me, carries a 1911. We went out back behind his house to shoot (he has lots of property and a home-built shooting range and backstop... pretty sweet) and then came inside to clean the guns. He did a full detail strip on his gun, because he likes to do it at least once a year. I really don't see it as being necessary that often, but to each their own. So as he started breaking down his 1911, I started running a few patches through my AK. I clean my AK a little more often than most because my house is slightly damp and the surface begins to rust quickly unless I keep it cleaned and oiled.

Once finished with the AK, I started to field strip my 1911. At this point, Jim had finished breaking down his pistol and was busy cleaning parts. I finished cleaning and reassembling my 1911 as he was about halfway through reassembling his gun. I performed a function test, inserted a loaded mag, pointed the gun at Jim's bucket of sand, dropped the slide, holstered the gun, and topped off the mag. A few minutes later, Jim did the same thing, only it went MUCH differently for him when he tried to load the gun. He inserted a loaded mag, pointed his gun at the sand, and dropped the slide. Instantly, the gun discharged... AND WENT FULL AUTO. Yes, that's right... All eight round dumped out of the gun in about 2 seconds. 2 rounds ended up in the sand, and the other six left a line of bullet holes in his floor.

So what happened?

I was watching him when this happened, and his finger was nowhere near the trigger. After the incident, I took the gun to inspect it and see if I could find the issue. I took the slide and racked it back and forth several times. The hammer stayed back. I was looking for how this gun could have discharged without the trigger being touched. Then, I racked the slide back and let it slam shut. BINGO! Hammer dropped. I did it again, hammer dropped again.

You see, when checking for slide/hammer function, I used to only do what I described, racking the slide back and forth several times, holding onto the slide the whole time. Jim did the same. But doing this did not produce the hammer drop. Only dropping the slide freely to battery did it. So what happened was:

Jim inserted fully loaded mag and dropped the slide.

When the slide got to battery, the hammer dropped, firing the round it had just chambered.

Gun cycled properly, ejecting spent shell, and dropping the hammer as soon as the next round was chambered.

This repeated until the mag was empty, and the slide locked to the rear.

So WHY did this happen?

Two words: Sear spring. He and I began to detail strip the weapon again, looking for anything out of place. When we removed the mainspring housing and grip safety, I looked at the sear spring. I couldn't really place what was wrong, but something did not look right. I removed the sear spring and put it back in, and it looked good. That's when I realized it! One of the 3 "prongs" on the sear spring wasn't in the right spot. I wish I had taken a picture before fixing it, because I can't for the life of me remember which prong it was, that was behind a part that it should have been in front of.

Moral of the story:

1. Pay very close attention when installing your sear spring. One piece in the wrong spot, and you could just have a dangerous malfunction on your hands.

2. Ever since this incident, my routine function check involves loading a snap cap into a mag and dropping the slide on it to see if the hammer follows. If no snap cap is available, I drop the slide on an empty chamber. Yes, I know it does additional wear, but I'd much rather be sure before possibly unloading an entire mag into my wall.

3. Follow the rule that saved Jim's ass: Keep that firearm pointed in a safe direction at ALL times, and if you screw up or something goes wrong, then all you have to do is explain that loud noise.

[Gun]

One of the 3 "prongs" on the sear spring wasn't in the right spot. I wish I had taken a picture before fixing it, because I can't for the life of me remember which prong it was, that was behind a part that it should have been in front of.

The prong on the left is the sear prong. If this prong were behind the sear (how this happens is beyond me as the sear spring lays across all three pressure points), the sear-trigger tension is null. Part of the function test is to drop the slide on either a snap-cap, or an empty chamber, which indicates either improper installation, or weak spring tension. Generally this is more of a problem with light trigger pull setups, as the setup is near the end of what is serviceable.

I detail strip, maybe once a year. I never go off of memory, review the strip thru resources, because the sear spring install is critical.

[PocketProtector]

The sear or hammer must be very worn or modified, should the hammer not stopped at half cock?

[snakeman21]

The sear or hammer must be very worn or modified, should the hammer not stopped at half cock?

I wondered that myself, but after correcting the issue, everything works as it should... Including the half-cock. And we checked parts, his gun is newer than mine, unmodified except for the grips, and none of the parts were considerably worn. Most of mine are more worn than his (which still isn't much at all). After reassembling his pistol with the sear spring properly installed, we tried and tried to see if it would do it again, but the pistol worked flawlessly. We brought it out back and shot it a bit more and had no issues. He plans on having a gunsmith look at his parts when he can, but we're thinking it was only user error on his part when he improperly installed the spring.

[harold63]

The sear or hammer must be very worn or modified, should the hammer not stopped at half cock?

There has to be adequate pressure from the spring to stop at half cock. If it was as the OP says, there was no pressure at all, which is an extreme case and will cause a full auto malfunction. There was no way to stop it at half cock. A function test before loading any ammo would have revealed this.

[harold63]

I wondered that myself, but after correcting the issue, everything works as it should... Including the half-cock. And we checked parts, his gun is newer than mine, unmodified except for the grips, and none of the parts were considerably worn. Most of mine are more worn than his (which still isn't much at all). After reassembling his pistol with the sear spring properly installed, we tried and tried to see if it would do it again, but the pistol worked flawlessly. We brought it out back and shot it a bit more and had no issues. He plans on having a gunsmith look at his parts when he can, but we're thinking it was only user error on his part when he improperly installed the spring.

The sear spring has to provide pressure for the gun to stay cocked when dropping the slide. It is why very light triggers can go full auto. Also, the pre travel and over travel needs to be adjusted correctly or the half cock still will not work. A good way to check to be sure your detail strip went correctly in reverse is to simply (NO AMMO IN GUN, PLEASE, AND NO MAG IN GUN) pull the trigger and hold it while racking the slide and letting it go into battery. You do not have to let it slam into battery. When it is in battery, let go of the trigger, slowly. You should feel the trigger reset. If there is no sear spring pressure, this will not happen and you know right then to disassemble and start over. If the trigger does pass the reset function check, then you can dry fire one or two times to be sure the trigger has adequate pressure on it and the sear is holding the hammer like it is supposed to. You say the parts are stock and unhoned, so that definitely rules that out, and broken hooks are hard to miss, though i suppose it could be overlooked if the person is not experienced.

[crazy charlie]

Thanks for the post and giving us a 'head's up'.

[sl315]

The sear spring has to provide pressure for the gun to stay cocked when dropping the slide. It is why very light triggers can go full auto. Also, the pre travel and over travel needs to be adjusted correctly or the half cock still will not work. A good way to check to be sure your detail strip went correctly in reverse is to simply (NO AMMO IN GUN, PLEASE, AND NO MAG IN GUN) pull the trigger and hold it while racking the slide and letting it go into battery. You do not have to let it slam into battery. When it is in battery, let go of the trigger, slowly. You should feel the trigger reset. If there is no sear spring pressure, this will not happen and you know right then to disassemble and start over. If the trigger does pass the reset function check, then you can dry fire one or two times to be sure the trigger has adequate pressure on it and the sear is holding the hammer like it is supposed to. You say the parts are stock and unhoned, so that definitely rules that out, and broken hooks are hard to miss, though i suppose it could be overlooked if the person is not experienced.

300WM - I recently had a trigger job on my 1911 and feel that something might not be right. Just want your opinion. The trigger pull was reduced from 5.5# to 3#, but I feel that the trigger reset is not that apparent as before. The reset is shorter, but I can't feel that snap back as before the trigger job. It seems like when I release the trigger, there is a slight pause and then I could faintly fell the reset. Is this normal after a trigger job?

[Noah_Zark]

Snakeman:

When I read the OP and saw "detail strip" and later "full auto" I immediately thought "sear spring". I learned about the 1911 sear spring in 2111 school at APG in early '73. Not the "hard way" but it was actually demonstrated by the instructor when we were covering the M1911A1.

Many 1911 fans may not have experienced this, and you have incoming rep for letting folks know about it. Most importantly, I'm glad that no one was injured. Unexpected FA is always a surprise.

Noah

[snakeman21]

Snakeman:

When I read the OP and saw "detail strip" and later "full auto" I immediately thought "sear spring". I learned about the 1911 sear spring in 2111 school at APG in early '73. Not the "hard way" but it was actually demonstrated by the instructor when we were covering the M1911A1.

Many 1911 fans may not have experienced this, and you have incoming rep for letting folks know about it. Most importantly, I'm glad that no one was injured. Unexpected FA is always a surprise.

Noah

He actually did very well controlling it, I wouldn't have been surprised if he'd dropped the gun out of surprise... or let the muzzle go so high as to put a few rounds into the wall or even the ceilling. But he managed to get two in the sand, and the other six were only a few inches apart in the foor. It helps that he had the gun low, only a couple of inches above the sand.

I was amazed at just how fast it was... I've seen semi's go full auto before, and I've experienced a full auto AK and an M4, but it seems the 1911 has a much higher rate of FA fire. All eight rounds were gone before we even knew what was happing. After getting home and looking it up, I found that if a 1911 goes FA or is modified to be FA, the cyclic can be over 1000 RPM! I don't think ours was quite that high, but it certainly beat the ROF for anything FA I've ever experienced. It sounded more like an incredibly loud, short roar than eight individual shots.

I just keep thinking about what would've happened if he'd dropped the gun and it started throwing rounds in every direction till the mag ran dry.

Noah, perhaps you know... Why didn't the hammer stop at half cock? Does the improper sear spring placement negate that as well?