M-60 question


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4v50 Gary
March 11, 2013, 12:10 AM
So I just read Presidio Press' book, Brothers, the story of two blacks who fought in Viet Nam. One was leg infantry and the other airborne.

Anyway, the infantryman got stuck with the M-60 and in a combined arms assault (infantry, cavalry and tanks) they expected high casualties. The NVA already took out one tank when they did their reconnaisance by fire. When the second assault came, he overwhelmed the NVA with his M-60. He didn't fire seven shot bursts but continual belt long bursts. He totally dominated them with accurate and sustained fire. Guys identified targets and he hosed it. When it was over, the NVA fled and he earned the DSC.

He commented that when the M-60 heated up as it did, it would rattle apart. Metal expansion saw pins work their way out. The tray cover would pop and the gun would seize up.

I think it's possible considering the way it was used, but can anybody confirm it?

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Devonai
March 11, 2013, 12:25 AM
My Guard unit still had Sixties when I first got there. Similar warnings abounded about working the gun too hard, though we were more worried about a runaway gun than total structural failure. I had fun with it until we got the M-240B.

12Bravo20
March 11, 2013, 08:23 PM
I carried a M60 for most of my time in the Army. I got the barrel hot enough to bend slightly (warp), I've had cook-offs, but never got one hot enough to fall apart from heat expansion. Not saying that it couldn't happen, just that it never happened to me.

Robert
March 11, 2013, 10:41 PM
My only experience with one was using blanks, but I did manage to set a small portion of the Air Force Academy on fire with one. Danged public university ROTC kids...

Nasty
March 12, 2013, 05:00 PM
I have a lot of experience with the 60...got the barrel glowing a few times but never had anything fall off.

I have also never seen "accurate and sustained fire" with one. The 60 is a suppression tool...you don't fire at individuals, you fire at an area, or rather, in front of an area. The expectation is that both primary projectiles (the bullets) and secondary projectiles (rocks kicked up) will pin the enemy down or take them out.

You don't snipe with a 60.

Sometimes those decorations utilize a bit of creative writing in them...this does not take away from what he accomplished, it only reflects that the document was nto written by a gunner.

rcmodel
March 12, 2013, 05:15 PM
I'm wondering how you get a 'cook-off' with any MG that fires from an open bolt, like the M-60??

The only way a round could cook off is if it was a mis-fired dud round, and stayed in the chamber long enough to get hot enough to cook off.

rc

backbencher
March 12, 2013, 06:07 PM
rc, how then does a "Runaway gun" occur? Every time I go to qualify or shoot a M249 or M240, we are warned about what to do if we have a "runaway gun." Would that be if the sear somehow fails to stop the bolt? It's even simulated in the EST-2000 simulator if you fire continuously @ a target, I think.

RustHunter87
March 12, 2013, 06:47 PM
a few rounds cook off at the end of this video
http://www.youtube.com/watch?v=X8rHKGkaOQk&feature=player_detailpage

MasterSergeantA
March 12, 2013, 07:00 PM
rc, how then does a "Runaway gun" occur? Every time I go to qualify or shoot a M249 or M240, we are warned about what to do if we have a "runaway gun." Would that be if the sear somehow fails to stop the bolt? It's even simulated in the EST-2000 simulator if you fire continuously @ a target, I think.
Normally it is from an excessively worn or broken sear. It can also happen in semi-auto firearms if the sear is too worn to engage the hammer and it essentially slam-fires until empty. Quite a significant emotional event, I am told.

Ian
March 12, 2013, 07:25 PM
The problem (well, one of them) with the M60 is that if you only pull the trigger just far enough to fire, the bolt will bump into the sear as it goes back and forth. Over time, this wears down the sear, eventually getting to the point that the bolt will just jump over the sear even when the trigger is fully released. That results in a runaway gun.

I've never experienced it, but my understanding is that the correct action in case of a runaway is to twist the belt so that it jams in the feedway.

As for guns coming apart when heated up, I haven't heard that from the folks I've talked to. The construction was relatively light to save weight, though, and I wouldn't be surprised if heavily used guns would start to have pin holes egg out or rivets and welds crack or loosen. That could easily be mistaken as being caused by overheating by someone putting a lot of ammo through one of them.

backbencher
March 12, 2013, 07:34 PM
We were told NOT to twist belts if we didn't want our digits massaged by the tender bolt & feed mechanism.

rtz
March 12, 2013, 07:59 PM
What's the alternative to twisting the belt?

rcmodel
March 12, 2013, 08:12 PM
Hang on and let it run till it runs out of ammo.

Twisting a cloth belt, or twisting and breaking a disintegrating link belt to stop a runaway gun is almost as old as MG's.

I imagine Hiram Maxim and John Browning did it a lot more then once in the development stages of early MG's.

And I still stand by my orginial questioning statement.
An open bolt MG cannot experince a 'cook-off' because there is never a live round in the chamber until the bolt chambers and fires it.
(unless the round is a dud and did not fire when it was chambered for whatever reason)

A closed-bolt auto like an M-16 can have a cook-of in a hot barrel.
Because a live round is chambered every time it fires, and can remain unfired in the chamber until it gets hot enough to cook off.

An open-bolt design cannot.
Thats why all successful MG's of the last century feed & fire from an open bolt.

As for the Youtube vid?
Just because somebody can afford a 5 or 6 figure M60 and enough ammo to melt it, doesn't necessarly mean they know what a cook-off is either.

rc

paintballdude902
March 12, 2013, 08:25 PM
rc, how then does a "Runaway gun" occur? Every time I go to qualify or shoot a M249 or M240, we are warned about what to do if we have a "runaway gun." Would that be if the sear somehow fails to stop the bolt? It's even simulated in the EST-2000 simulator if you fire continuously @ a target, I think.

it can happen from any semi or full auto. ive heard stories of it happening to the 40mm bofors caused by a worn part. they simply let it run out of ammo.

ive also heard allot of stories of "it can happen" to the 25mm gau-12. but i dont recall ever talking to anyone that ever had it happen

rcmodel
March 12, 2013, 08:37 PM
The only possible way "it can happen" to the 25mm gau-12, or any other of the Gatling Gun aircraft cannons, would be a stuck electrical solenoid or wiring short.

They are spun up to speed by an electric motor, and nothing else can possible make the gun run away, or even fire once, unless the electric motor is spinning them out of control and there is no way to shut off the electricity to it.

Even then I'm pretty sure there are other controls / shut-off's / fail-safes on the arming switches, feed troughs, and ammo cans that would have to be shorted out of commision too before the gun could run away.

rc

Billy Shears
March 12, 2013, 09:31 PM
An open bolt MG cannot experince a 'cook-off' because there is never a live round in the chamber until the bolt chambers and fires it.
(unless the round is a dud and did not fire when it was chambered for whatever reason)

A closed-bolt auto like an M-16 can have a cook-of in a hot barrel.
Because a live round is chambered every time it fires, and can remain unfired in the chamber until it gets hot enough to cook off.

An open-bolt design cannot.
Thats why all successful MG's of the last century feed & fire from an open bolt.
Not true. The M2 BMG fires from a closed bolt, and given that it's currently the oldest small arm in our arsenal, and in use with all our NATO allies, and lots of other countries besides, I'd certainly say it would have to be called a "successful" MG.

And for that matter, all the various Maxim variants -- certainly successful MGs as well -- fired from the closed bolt, as did the water cooled Browning M1917. When the gun was redesigned as an air cooled weapon, and designated the M1919, it was changed to fire from the open bolt. The water cooled version, which remained in use during WWII, always fired from the closed bolt, however.

rcmodel
March 12, 2013, 09:34 PM
O.K>!
You got me there.

But an M-60 doesn't fire from a closed bolt, and even if it has it's short-comings, cook-off's isn't one of them.

rc

yaonttwo
March 12, 2013, 10:00 PM
M60 was the biggest piece of crap ever made. Constantly jammed and would knock the fillings our of your teeth (helicopter use hung from a bungie cord)

yaonttwo
March 12, 2013, 10:05 PM
M60 was the biggest piece of crap ever made. Constantly jammed and would knock the fillings our of your teeth (helicopter use, hung from a bungie cord)

rcmodel
March 12, 2013, 11:22 PM
Apparently experiences differ.
I used the M-60 off & on from 1964-70.
I liked the M-60, A lot!

Perhaps if you had used or humped a Browning .30 MG & tripod before the M-60 came along, your view of them would be different too?

They were never designed to be hung or fired from a bungee cord in the first place.

That was a result of a lack of proper helo mounts, and field expedient methods to improvise and overcome during Viet Nam.

The new Huey doors & the new M-60 crossed paths faster then the two could be adopted to each other.

I'll just say you were much better off with a M-60 hanging on a bungee cord then a Browning .30 hanging on a Bungee cord!

And leave it at that.

rc

TCBPATRIOT
March 12, 2013, 11:44 PM
My wife's uncle has a colt gold cup that will do mag dumps because it is so worn out.

Irtys
March 13, 2013, 12:30 AM
I used an M-60 in Viet Nam as a door gunner, I think it was one great gun. That is until the mini gun.

Jeff White
March 13, 2013, 12:32 PM
Quite a significant emotional event, I am told.

There is nothing emotional about a runaway gun with an M60. All you need to do is reach up and twist the belt to break it. It will not pull your fingers into the feed mechanism, it doesn't move that fast and I have personally done it more then once. Or you can reach back and open the catch that holds the feed cover closed and let it raise an inch or two. That will stop the ammo from feeding into the gun.

As to the original question, I have never seen nor heard of a receiver shaking itself apart from continuous firing. However unless it is safety wired together the gas system will vibrate apart.

MutinousDoug
March 13, 2013, 03:52 PM
The M-60s we used in 1970 held up well for us. Someone would burn out a barrel fairly regularly so each AG carried a spare for their gun. I know we once had a cracked bolt lug but it wasn't discovered until the gun was broken down for cleaning after action so there was little drama associated with that discovery. We started carrying spare bolts after that though.
We were 1st Cav so the door gunners for the slicks were recruited from our gunners when they were getting short so we kept in touch when we'd see them and I don't recall any complaints from those guys. They used their guns more often than us but had better access to the maintenance shops. The slicks all had pintle mounts. I think some of the Loches (LOH: scout or "light observation helicopters") hung guns from webbing straps. I can't imagine trying to accurately shoot an M-60 hung from a bungy.

LeonCarr
March 13, 2013, 04:00 PM
My Dad (25th Infantry RVN 68-69) said he never saw an M-60 (He called it "The Pig" during our conversation) self-disassemble like that, but he has seen barrels get hot enough to light cigarettes and cigars on contact.

Just my .02,
LeonCarr

Capstick1
March 13, 2013, 06:56 PM
The M60 was and still is a piece of crap. When I was in the Air Force I had to qualify on it off and on for the first twelve years of my career. Anything that's not safety wired on it is guaranteed to break or loosen up on it. Whenever we'd go out to qualify on it we would usually have to bring 3 or 4 extra ones with us to keep on standby in case we had had a gun go down. This happened quite frequently and we would either cannibalize parts from the extra guns or use the whole gun. I've seen just about everything break on the M60. Oprods, firingpins, firing pin springs, recoil springs, bolts, trigger sears (A "Runaway gun" can really raise the pucker factor) The Air Force eventually got rid of the M60's and replaced them with the much more reliable M240 machinegun. Today I wouldn't take an M60 if someone gave one to me for free. They're junk and should have been scrapped a longtime ago.

DesertFox
March 13, 2013, 07:21 PM
Need to pick one up on the C&R.

12Bravo20
March 13, 2013, 10:00 PM
The only mechanical failure I ever had with any of the M60s I carried was a broken extractor once (caused by some monkey dry firing it too much in the arms room) I have had a run away a few times with the M60. It depended on how much ammo was left on the belt on if I would grab and twist. To me, the M60 is like any old car, you have to know the little tweaks and tricks to keep them humming along. I liked the M60 all the years I carried one.

backbencher
March 13, 2013, 11:15 PM
It sounds like folks who got new M-60s really liked 'em, and folks who got really old M-60s really hated 'em. Having humped a M-60 @ OCS, I far preferred that to humping a M240. I wonder if the stoppage problems w/ the M-60 that led the Army to the M-240 had more to do w/ the relative age of the weapons than any fault of the M-60 design?

kBob
March 13, 2013, 11:25 PM
I liked it better than the FN MAG as the british used it, the French AA1 GPMG, and MG-1 through MG3 all of which I had hands on and rounds down range experience with.

As a GPMG I liked it better than a 1919 Browning though as a heavy as in from the tripod (and if I did not have to carry it) the 1919 was better.

Our A gunners carried a Spare barrel bag (besides the spare barrel this had the asbestos glove and the cleaning gear,and the T&E mechanism) a tripod with the mount on it, a pair of bolt cutters (don't ask), his personal gear and an M1911A1. My unit SOP was that the holster was on the left side and so reversed as in butt forward carry.

-kBob

Dave Rishar
March 15, 2013, 06:17 PM
We were still using the D model right up into the early 00's in some commands. They did not often shake loose but it happened occasionally. I seem to recall all the very important fasteners being secured by lockwire or (in the case of the trigger housing), a flat spring. Depending on the condition and age of the weapon, the spring didn't always work as well as it should have.

And yes, they could be quite accurate, particularly when prone. Between the weight, buffer, and low rate of fire, recoil was a gentle, minor push. It was even possible for a big fella to shoot one accurately off the shoulder, but one had to be fairly strong to hold it up for any length of time due to the weight. Again, the recoil wasn't an issue.

Theoretically, one of the issued two barrels would have a weird zero; the front sights were not adjustable and the rear sights weren't on the barrel, meaning that only one of two barrels would be zeroed at any given time. In practice it didn't seem to matter much.

This may or may not apply to the story in question. I'm not sure how much the D differed from what was used in Vietnam but as I understand it, they were pretty similar.

Big Al Mass
April 1, 2013, 02:02 AM
When the gun was redesigned as an air cooled weapon, and designated the M1919, it was changed to fire from the open bolt.
The M1919A4 (which is what you are most likely referring to) was a closed-bolt gun. However, the South African Vektor-made copy, known as the MG4, was modified to fire from an open bolt.

MaterDei
April 1, 2013, 08:48 AM
I was on OCS instructor for 4 years and taught hundreds of people how to properly deploy the M-60.

Jeff is right, the proper thing to do with a runaway is to snap the belt by twisting it and letting the gun feed and fire the last few rounds.

With regard to the OP's question, I've never seen one fall apart due to heat. I have seen barrels get red hot though. We taught and enforced a 6 - 9 round burst rule but during final protective fire (FPF) drills, there is no such thing as bursts. You run until told to stop or your ammo runs dry.

hdbiker
April 1, 2013, 11:33 AM
I had a M60 run away on me in training at Fort Leonardwood Mo, in basic training back in 1963.I was prolly the tenth guy in line to fire a 100 round belt in the M60.My turn came and the first burst went fine,the second try and it just kept fireing.I glanced up at the Range Officer and he just smiled and let it go.The M60 was smoking hot. hdbiker

Coop45
April 1, 2013, 04:36 PM
Running out of ammo before running out of NVA was our biggest problem.

Flfiremedic
April 7, 2013, 11:19 AM
We were taught to break the belt with a runaway 60...but not to grab the bolt...

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