Weird thing happened at the range today.

jc75754 · #1 10-23-10, 23:46

I went to the range today and had a great session, but that is not the weird part. A guy in the lane beside me was firing his DD M4 V3 and as he was shooting the gun went into a burst about every third trigger pull. It took me by surprise b/c they don’t alloy NFA weapons at this particular range. I peeked in his booth and asked him if it was a NFA weapon and it was not. I had my DD M4 with me and we compared later after he finished and I could not tell any difference between the two. What kind of defect could cause the rifle to do this. I recommended that he contact DD and ship it back to them, but still i am curious if this could have damaged his rifle.

Bolt_Overide · #2 10-24-10, 00:01

Could be a lot of things, one of the more likely culprits in my experience is a home brewed "trigger job", that is of course given that there was nothing wrong with the rifle when it shipped.

jc75754 · #3 10-24-10, 00:07

When I talked with the guy he seemed a little freaked. He had just bought the rifle a couple of weeks ago and it was his first trip to the range. He only fired 1 mag maybe two. Lets assume for the moment that it is not a "custom trigger"

Mac5.56 · #4 10-24-10, 01:40

Two guys in lanes next to one another both happen to own DD M4 V3s?
That's odd...

I would tell that person to put the gun down, un-load it, and call DD right away.

DaBears_85 · #5 10-24-10, 02:21

From what little I know about his particular weapon and given the circumstances/situation, I'd say it has something to do with either the disconnector, disconnector spring, or both. He definitely needs to stop firing the rifle immeadiately and contact DD.

Col_Crocs · #6 10-24-10, 02:30

Assuming it's not a trigger job, I agree with it possibly being his disconnector, disconnector spring, or both. That said, taking the trigger job out of the equation still leaves a lot of questions.
1. Did you or he function check the weapon when you compared weapons?
2. Was it new when he got it?
3. Who did he get it from?
4. Was it ever taken apart by him or the seller?

RAM Engineer · #7 10-24-10, 08:09

I had an early DD M4 that did this. Mine was actually doubling instead of burst firing. I contacted DD and they had me send the lower back. They returned it to me with a note saying they replaced the disconnector and all was now good. The doubling continued. Their customer service guy asked me if I had any known good fire control parts I could change out with. I used some Colt parts to try but the selector switch wouldn't fit into the gun because it was hitting the top rear of the disconnector. DD asked me to send the whole gun back and they sent me a new lower with my upper on it.

I test fired the new lower enough to verify that it was ok and then sold the rifle.

jc75754 · #8 10-24-10, 19:37

Thanks! This gentleman has contacted DD and is awaiting a response.

Popsmoke · #9 11-10-10, 21:22

I have a Springfield Socom 16 that did that. I was trying to slow fire very accurately and had a very slow trigger squeeze.
My theory is that while applying constant pressure to the trigger, when the rifle fires and recoils, my finger was still applying pressure while recoiling and thereby inadvertently making another trigger squeeze.

Just a theory: battle rifles are meant more a trigger pull than a benchrest squeeze and follow through.

Captains1911 · #10 11-10-10, 22:20

Are you sure "he" was not accidentally bump-firing?

Grumpy MSG · #11 11-10-10, 23:23

What you have in that circumstance is probably a rifle that would fail a "Functions Check". what is happening is the rifle is firing when you pull the trigger and then again when you release it. On an AR there are in essence 2 hooks, one that is used to release the hammer, it is located at the base of the hammer. it is just a notch on the hammer and the front of the trigger slides down when you pull it and it releases the hammer the other is more obvious and looks like a hook, it catches the hammer when the bolt carrier cycles to the rear. When you release the trigger it slips off that hook and catches on the notch. If a rifle fails the "Functions Check" what happens is the hammer slips from the second hook and falls completely because it wasn't able to catch on the notch. In theory if you hit just the right spot and held it on a rifle like that it would be capable of firing auto with the trigger held in that exact spot. In reality, usually because of recoil and the fact you are releasing the trigger it fires once when you pull it and once when you release it. If you do the slow pull, hold and then release, it will fire twice with one pull. If you do the quck pull and release it will seem to fire a burst.

Any way you look at it he did the right thing by contacting the manufacturer and get them to make it right.

Suwannee Tim · #12 11-13-10, 06:15

Quote:

My theory is that while applying constant pressure to the trigger, when the rifle fires and recoils, my finger was still applying pressure while recoiling and thereby inadvertently making another trigger squeeze.

I've had this happen to me twice, two guns on the same day, an M1A and a Kel Tec LCR. Each doubled once, never happened before or since. I shot them for a while with a dummy cartridge in the magazine before I regained confidence.

If you have a firearm go full auto you should quit using it at once. I recall the BATFE has prosecuted at least one person for possession of an illegal machine gun. This person claimed the gun was malfunctioning yet he continued to use it.

Iraqgunz · #13 11-13-10, 14:40

If you are referring to that Olofsun cat, he actually KNOWINGLY installed an M16 FCG into the weapon and then KNOWINGLY loaned it out even after it fired in auto.

Quote:

Originally Posted by Suwannee Tim

I've had this happen to me twice, two guns on the same day, an M1A and a Kel Tec LCR. Each doubled once, never happened before or since. I shot them for a while with a dummy cartridge in the magazine before I regained confidence.

If you have a firearm go full auto you should quit using it at once. I recall the BATFE has prosecuted at least one person for possession of an illegal machine gun. This person claimed the gun was malfunctioning yet he continued to use it.

Suwannee Tim · #14 11-13-10, 16:17

The case I'm thinking about, the rifle was defective, not modified. I searched for it but I can't find what I am looking for. I didn't think you could install M16 trigger parts in an AR. Doesn't the M16 have one pin more than an AR?

Grumpy MSG · #15 11-13-10, 21:07

Quote:

Originally Posted by Suwannee Tim

The case I'm thinking about, the rifle was defective, not modified. I searched for it but I can't find what I am looking for. I didn't think you could install M16 trigger parts in an AR. Doesn't the M16 have one pin more than an AR?

You are correct about the M4/M16 having one more pin (it also has a few different parts), but most of the pieces will actually go in an AR without any modification (the piece on the extra pin will not go) and the rifle should fire semi-auto only. The Selector would rotate to where Auto would be, but it will only fire semi-automatically in that position too. In fact a lot of the early knock off ARs sold in the '80s used modified M16 parts. There was a time, if your rifle had any M16 fire control parts it would be deemed a machinegun by the BATF. You could use the parts if they were rendered unusable in an auto firearm bt modifying them by shortening one piece, welding a little spot on another and cutting off a hook.

Quote:

Originally Posted by Suwannee Tim

My theory is that while applying constant pressure to the trigger, when the rifle fires and recoils, my finger was still applying pressure while recoiling and thereby inadvertently making another trigger squeeze.

The way to perform a "Functions Check" on a Semi-Auto firearm is to clear the weapon(Normally: Attempt to place on safe, remove the magazine, pull the bolt/ slide to rear and ensure chamber is clear, if it didn't go on Safe earlier, place it on Safe now) attempt to pull the trigger with it on Safe. The weapon shouldn't fire. Move the safety to Fire, pull and hold the trigger, cycle the bolt/ slide, slowly release the trigger. On an AR you should here a metallic click, but the hammer should not fall. Then pull the trigger and the hammer should fall. On the M4/16 it is recommended that you do this 5 times, the hammer should never fall. You can also perform this check with the lower receiver, by working the hammer by hand.

If your theory were correct you would have to pull the trigger just enough to fire, and then have recoil pull the rifle back away from your trigger finger (your grip would have to be pretty loose) and then as the recoil/ buffer/ operating rod spring pushed the bolt forward it would bump the trigger back against your finger causing the rifle to fire again. It's not impossible that that would occur, but it is improbable. People have a tendency to fire Semi-Auto firearms two different ways, squeeze the trigger and hold until everything stops moving, then release the trigger, or squeeze the trigger until the weapon goes off and release immediately, usually even before the rifle stops recoiling. If you had trigger group issues, the first would fire when you pulled the trigger and fire sometimes when you released it. The latter would make the rifle seem like it was firing a 2 round burst.

Thomas M-4 · #16 11-13-10, 22:01

Either the FCG is fouled up or he was bump firing it.

Iraqgunz · #17 11-13-10, 23:50

Every part of an an M16 FCG will fit an a lower that has .155 diameter holes. The auto sear will not unless it has been drilled for it. The auto sear is not what makes your gun go multi bang.

Quote:

Originally Posted by Suwannee Tim

The case I'm thinking about, the rifle was defective, not modified. I searched for it but I can't find what I am looking for. I didn't think you could install M16 trigger parts in an AR. Doesn't the M16 have one pin more than an AR?

Iraqgunz · #18 11-13-10, 23:54

Have you actually ever installed a complete M16 FCG into an regular AR minus the auto sear? If not, you might be surprised at what happens when you do and then rotate the selector lever. Unless you have some wonky lower receiver with a sear block every piece of the M16/M4 FCG will fit, with the exception of the auto sear.

Quote:

Originally Posted by Grumpy MSG

You are correct about the M4/M16 having one more pin (it also has a few different parts), but most of the pieces will actually go in an AR without any modification (the piece on the extra pin will not go) and the rifle should fire semi-auto only. The Selector would rotate to where Auto would be, but it will only fire semi-automatically in that position too. In fact a lot of the early knock off ARs sold in the '80s used modified M16 parts. There was a time, if your rifle had any M16 fire control parts it would be deemed a machinegun by the BATF. You could use the parts if they were rendered unusable in an auto firearm bt modifying them by shortening one piece, welding a little spot on another and cutting off a hook.

The way to perform a "Functions Check" on a Semi-Auto firearm is to clear the weapon(Normally: Attempt to place on safe, remove the magazine, pull the bolt/ slide to rear and ensure chamber is clear, if it didn't go on Safe earlier, place it on Safe now) attempt to pull the trigger with it on Safe. The weapon shouldn't fire. Move the safety to Fire, pull and hold the trigger, cycle the bolt/ slide, slowly release the trigger. On an AR you should here a metallic click, but the hammer should not fall. Then pull the trigger and the hammer should fall. On the M4/16 it is recommended that you do this 5 times, the hammer should never fall. You can also perform this check with the lower receiver, by working the hammer by hand.

If your theory were correct you would have to pull the trigger just enough to fire, and then have recoil pull the rifle back away from your trigger finger (your grip would have to be pretty loose) and then as the recoil/ buffer/ operating rod spring pushed the bolt forward it would bump the trigger back against your finger causing the rifle to fire again. It's not impossible that that would occur, but it is improbable. People have a tendency to fire Semi-Auto firearms two different ways, squeeze the trigger and hold until everything stops moving, then release the trigger, or squeeze the trigger until the weapon goes off and release immediately, usually even before the rifle stops recoiling. If you had trigger group issues, the first would fire when you pulled the trigger and fire sometimes when you released it. The latter would make the rifle seem like it was firing a 2 round burst.

joe-bananas · #19 11-16-10, 01:09

I had a Valmet M82 in the mid-80s that began doubling and tripling on while we were out on an all-day shoot.

After a couple of mags of this, I field stripped the weapon, checked the springs, bolt, carrier, gas system, etc. Nothing out of the usual.

I shot another mag, same thing.

I gave up, packed it up and resigned myself to sending it to Valmet.

Their customer service was fantastic. The cause? Remanufactured ammo with soft primers. After that it was fresh, mil-spec, zero-mileage ammo for me, no matter what firearm.