Winston Smith | 03 May 2016 4:57 p.m. PST |
So, I guess you have to replace the barrels if they are in continuous use to prevent overheating. What happens if you don't? And if you replace a barrel, can it be reused once it cools down? How many spares did an average machine gun have on hand? How easy is it to replace? Have I left out any pertinent questions that an ignorant newbie should ask?
Feel free to suggest to Dear Editor in Chief Bill the appropriate boards to crosspost to. |
Rich Bliss | 03 May 2016 5:08 p.m. PST |
When a barrel overheats, it actually starts to sag. Which pretty much destroys your accuracy |
Weasel | 03 May 2016 5:17 p.m. PST |
Excessive heat can also cause rounds to "cook off" firing uncontrollably. Or that's what I was told when I did my mandatory military time. Regarding how many, from what I've read, ww2 era Bren guns were shipped with a single spare barrel "in the box". I don't know if the grunts would obtain more though I can imagine. On most squad machine guns, it's extremely easy to replace. |
Mako11 | 03 May 2016 5:17 p.m. PST |
Yea, they overheat, melt, and can seize up. I've read reports of them glowing so much you could see the bullets moving inside them. Don't know if that's true or not, but suspect that would be a major concern. Some barrels are easy to replace, in just a few seconds. Others, not. German WWII MG barrels were very easy and quick to swap out. |
wrgmr1 | 03 May 2016 5:32 p.m. PST |
In winter a hot barrel would cool off fast in the snow. In summer I've read were soldiers would use water or urine to cool it off. |
epturner | 03 May 2016 5:34 p.m. PST |
Bren gun barrels are easy to swop out. Not hard at all. I've done it as a re-enactor. (Cue the groans of wargamers about stuff re-enactors do…) Issue was one spare barrel with the other bits and bobs. Not much different than today with the M249. Now the more interesting question is for what reason do you need to know this, Winston? Shall I be reading about anything special occurring in far off Luzerne County? Eric |
jowady | 03 May 2016 5:38 p.m. PST |
I've always thought the urine story was an "old soldier's tale. Your body really doesn't produce large amounts and when a barrel is really hot you'll need a fair amount of liquid to cool it down. |
Cold Steel | 03 May 2016 5:40 p.m. PST |
We carried 2 barrels for the .50 cals and the M60s at the loader's hatch on our tanks in Korea. Switching barrels took only seconds. And yes, rounds will cook off when the weapon overheats. Once an M60 started, it would fire uncontrollably until it ran out of bullets. All you could do was twist the ammo belt off at the feed slot. The M240 co-ax did not have a spare barrel. A steady stream of cool air through the firing port kept it cool when firing. |
Rubber Suit Theatre | 03 May 2016 5:41 p.m. PST |
Stuff that can happen on an overheated gun: "cook-off" – rounds heat up and fire of their own accord. "runaway gun" – like cook-off, but on full auto. Stripped rifling. Warped barrel. Barrel welds to receiver. Weapon seizes. Barrel change for most US WWII weapons: YouTube link |
Graycat | 03 May 2016 5:58 p.m. PST |
I remember seeing a training film for barrel changing, on, I think, the M60, in my High School ROTC class. We saw many such films. Most were 10-20 years out of date; I'm pretty sure they were mostly an excuse for not really having a course schedule. "Why yes, I know how to service and maintain the Davy Crockett!" |
Weasel | 03 May 2016 6:05 p.m. PST |
Was the M60 the one that was issued with an asbestos glove? |
Cold Steel | 03 May 2016 6:11 p.m. PST |
|
Leadjunky | 03 May 2016 6:31 p.m. PST |
It is called barrel droop and no you can't take a pill for it. |
LostPict | 03 May 2016 7:13 p.m. PST |
While I was in NARMY training in 2006 at Fort Jackson, one of the tripod mounted M-2s started cooking off rounds when it over-heated. Quite Impressive! |
Saber6 | 03 May 2016 7:31 p.m. PST |
We had an M240 fuse the barrel to the receiver. They didn't notice any issues until the tried to take it apart. |
The Virtual Armchair General | 03 May 2016 8:08 p.m. PST |
A Marine Corps vet of Korea and that jolly morning when All The Chinese In The World launched their massive counter-offensive in the snows from north of the Yalu, told me he and his loader fired countless thousands of rounds from their air cooled .30 Caliber Browning barrel(s) until forced to pull out later that day. Located in a snow filled foxhole, their ammunition was constantly being replaced so that they could keep up more or less continuing fire as hordes of Chinese Regulars kept rushing their position. He told me the barrel they started with became radiantly red-hot, then began visibly to droop. At the first chance, they swapped the barrel out and laid it beside them, immediately going back to the business of shooting down any number of enemy soldiers. The second barrel soon enough began to go the same route as the first, but they kept firing whole belts until another break to swap out the barrel--only this time they discovered the first one, cooling in the snow, had re-solidified, hard and cold, in its previous bent shape. They were effectively out of business, but not out of Chinese…. The retreat from Chosin was next on the program. TVAG |
McKinstry | 03 May 2016 8:11 p.m. PST |
All the barrel issues mentioned on the M60 were real and a PITA. Spare barrel, asbestos glove and definite cook off tendencies. The HH-53 Jolly Greens had three mini-guns, one on each side and one on the tail ramp. Airflow cooled the sides just fine but the tail was always a bit of an issue and the cook off is not always instant. Nothing quite as randomly troublesome as being x minutes into a return flight post firing when bang, a round cooks off (just one, they didn't gang fire as an M60 might) headed out and down God knows where. The odds of anything getting hit were I suspect infinitely small but nevertheless, it was disconcerting. |
Rudysnelson | 03 May 2016 8:25 p.m. PST |
In 1978, my platoon were given several old MG barrels and the company commander fired them until they over heated and sagged. We counted rounds for the report to the higher command. We used regular .50 calls mounted on M551 so no copula guns. The gun glowed then got white, then sagged. A few more rounds were fired through the side of the barrel. Those short rounds were uncontrolled and spewed in every direction after they passed the barrel. Very dangerous even though we were in front of the firing line. Both barrels melted within 50 rounds of each other. |
goragrad | 03 May 2016 11:01 p.m. PST |
Read an account of fighting on Guadalcanal that claimed that when the barrels got red hot that the bullets were tumbling when they exited the barrels. Not sure you would be able to see that. |
Martin Rapier | 03 May 2016 11:16 p.m. PST |
Most LMGs were issued one spare barrel, carried by the loader. It doesn't take long to change them. Iirc for the MG34 it was recommended to change them every 250 rounds. No idea on the scale of issue for tripod mounted air cooled machine guns, but I would suggest at least one spare. Water cooled guns don't need the barrels changing unless they wear out. |
emckinney | 03 May 2016 11:22 p.m. PST |
Of course, this was the big advantage of the water-jacketed MGs like the Maxim and its derivatives. You could fire them nearly forever (at least until there was so much build-up in the barrels that other problems took over). |
Rrobbyrobot | 04 May 2016 4:41 a.m. PST |
I'm surprised no one has described the cork screwing of rounds leaving an over heated MG barrel. This occurs before the barrels actually melts. And the barrel is already a write off when this occurs. It happens because the rifling is burned out. The tracer rounds visibly fly in a widening spiral after leaving the barrel. Not good for accuracy. Also, such barrels are no longer useful. Back in my day. These were considered as expendable items requiring turn in. I did once see a Capt. take over an M60 on a range. He fired the weapon 'till the barrel sagged. Seemed to think it outrageously funny. The guy was a 'Nam vet and a helicopter pilot. He was relieved over that and some other incidents. |
Mugwump | 04 May 2016 4:45 a.m. PST |
My dad was in WWII. He told me of firing a machine gun so much that you could see the bullets traveling gown the barrel. The standard procedure was to detach the barrel, shove it into water and then reattach it to continue firing. Ordinance Steel is tough material. |
14Bore | 04 May 2016 2:06 p.m. PST |
If you would like to see what happens to small arm full auto there is videos on a Web site Bearing arms from around New Year or look on YouTube. They run full auto on a AR and a AK until they miss fire. |
jgibbons | 04 May 2016 5:39 p.m. PST |
Epturner has it correct for the Bren changes fast and easy even prone… One spare typically carried in a canvas case by loader with misc tools and other spare small replacement parts… On your other question – barrels can be used after cooldown (assuming they are swapped before permanent damage) |
Patrick R | 05 May 2016 3:24 a.m. PST |
Nice little Vickers factoid : The weapon had a reputation for great solidity and reliability. Ian V. Hogg, in Weapons & War Machines, describes an action that took place in August 1916, during which the British 100th Company of the Machine Gun Corps fired their ten Vickers guns continuously for twelve hours. Using 100 barrels, they fired a million rounds without a failure. "It was this absolute foolproof reliability which endeared the Vickers to every British soldier who ever fired one." |