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Posted: 9/30/2004 4:50:39 AM EST
I bet you didn't know you could get an M4A1 handguard to reach 315 degrees F external temperature!

stinet.dtic.mil/cgi-bin/fulcrum_main.pl?database=ft_u2&searchid=0&keyfieldvalue=ADA317929&filename=%2Ffulcrum%2Fdata%2FTR_fulltext%2Fdoc%2FADA317929.pdf

Apparently it isn't very good for the rifle though...

Quick highlights:

1) M4A1 barrel outlasted M16A2 barrel in test to destruction. First tested M4A1 barrel ran out of ammo before barrel burst. Second M4A1 barrel burst at 596 rounds in 3 minutes 32 seconds.

2) M16A2 barrel burst at 491 rounds in 2 minutes 49 seconds.

3) External barrel temperatures reached upwards of 1,500F and as high as 1,712F

4) The gas tube did not give before the barrel in any of the tests

5) Distinct change in sound and muzzle flash 30 rounds before barrel ruptured in all cases. Barrel had also drooped as much as an inch lower at the muzzle in all cases.

Final section of the PDF report also includes a list of all known accidents involving the M4A1 up until September 1996 and makes for interesting reading in itself.
Link Posted: 9/30/2004 5:05:58 AM EST
whoa 600 rounds in 3 minutes...thats what I call cookin with gas!
Link Posted: 9/30/2004 8:43:52 AM EST

Originally Posted By Bartholomew_Roberts:
3) External barrel temperatures reached upwards of 1,500F and as high as 1,712F



Yeah, the plastic XM8 definately sounds like a bad idea...

--------------------------



Aaaahhhhh!!!!!!
Link Posted: 9/30/2004 9:04:08 AM EST
In our barrel torture testing at MGI, I've seen handguards actually on fire!
I concur that the gas tube remains intact beyond the failure of the barrels.
Cookoffs occur much earlier than failure, and effectively disable the weapon from use temporarily.
M4 barrels will typically start cooking-off before 200 rounds are fired in full auto.

Much better barrels are required for full-auto use in a squad auto type role for the M16.
Barrel cooling technologies are also needed, so we can have lightweight barrels which will withstand extended full-auto firing.
We are working on it, and have some outstanding prototypes.
In the meantime, our QCB system allows quick change of barrels when hot or cold.
We are developing a modular AR platform to allow configurations from entry, to duty, to sniper, to squad auto LMG, all on the same upper and lower receivers, with quick change barrels, modular magwells, and even a belt-fed option, and open-bolt/closed bolt fire control, and different caliber usages. The MGI QCB upper receiver system is the first part that is available to the public. The modular lower receiver is next.
Link Posted: 9/30/2004 9:29:24 AM EST

Originally Posted By Bartholomew_Roberts:
... Barrel had also drooped as much as an inch lower at the muzzle in all cases.
...



Thanks. This confirms the story my Dad told me about the barrel drooping on his M16 in Vietnam. I had read many posts here that say the gas tube will melt before anything happens to the barrel, so I've never mentioned it before.

There's just too damned many experts here.
Link Posted: 9/30/2004 9:48:23 AM EST

Originally Posted By m193:

There's just too damned many experts here.




Link Posted: 9/30/2004 9:58:39 AM EST
This might be one of those doomed M4 barrels... Found it from AR15.com couple of years ago.

MN

Link Posted: 9/30/2004 10:07:40 AM EST
Link Posted: 9/30/2004 11:11:21 AM EST
[Last Edit: 9/30/2004 11:11:44 AM EST by Yojimbo]
Very interesting, I'd like to see this test repeated with identical 4140 barrels so we can see what kind of difference there is between 4140 and 4150.
Link Posted: 9/30/2004 11:19:11 AM EST
So the metal barrel heats up until it becomes maliable and the gas pressure pops it like a baloon. I'd love to see the muzzle flip around like a wet noodle in slow motion just before it pops.
Link Posted: 9/30/2004 11:26:33 AM EST

Originally Posted By Lumpy196:
Cool. Someone actually documented a test to prove once again that an assault rifle ISNT a SAW


Thanks Bart



Have the same tests been performed with the SAW? How about the M240?
Link Posted: 9/30/2004 11:37:19 AM EST
Damn, if I could afford two barrels, and the ammo, just for kicks.... I am tempted to set up hi-res video of something like this.

Anyone have any worn out barrels they wanna donate?
Link Posted: 9/30/2004 11:41:52 AM EST

Originally Posted By magnum_99:

Originally Posted By Lumpy196:
Cool. Someone actually documented a test to prove once again that an assault rifle ISNT a SAW


Thanks Bart



Have the same tests been performed with the SAW? How about the M240?



How about M2? I wouldn't want to be anywhere in the general vicinity when that thing goes.

Supposedly people have seen M2 barrels so hot that they can see the rounds going down the barrel, they get so hot that the bullet draws heat away from the barrel or something to that effect causing a the barrel to glow slightly bright in areas where the bullet is traveling.

I'd like to see that documented.

I'm not sure if I am ready to believe it or not, though the videos of the full auto firing while viewed by thermal imaging equipment was pretty interesting as you could see some temperature change in the barrel as bullets traveled through it.
Link Posted: 9/30/2004 2:00:00 PM EST
that's definitely a quality control issue.
Link Posted: 9/30/2004 4:07:07 PM EST

Originally Posted By magnum_99:

Originally Posted By Lumpy196:
Cool. Someone actually documented a test to prove once again that an assault rifle ISNT a SAW


Thanks Bart



Have the same tests been performed with the SAW? How about the M240?


I'm positive that they have been tested, as well as every other weapon in the inventory, but have no idea where the details of the results can be found.
Link Posted: 9/30/2004 8:27:29 PM EST
[Last Edit: 9/30/2004 8:28:07 PM EST by jonathan1994]

Originally Posted By JosephR:
that's definitely a quality control issue.



]
Link Posted: 9/30/2004 9:08:08 PM EST

Originally Posted By Yojimbo:
Very interesting, I'd like to see this test repeated with identical 4140 barrels so we can see what kind of difference there is between 4140 and 4150.



+1!

I would also like to see a head to head comparison of a light weight noodle barrel and an hbar.
Link Posted: 9/30/2004 9:10:34 PM EST
my buddy fired his M16A2 on burst till it caught on fire during a range excersize, the sargent just grabbed him another one and told him to keep shooting
Link Posted: 9/30/2004 11:16:57 PM EST
I personally have put 600 rds. througha saw barrell as fast as you can change the 200 rd drums. By the third one the heat coming from the weapon when reloading was painful. My driver who was directly underneath the weapon said he could see rounds pass through the barrell. I couldn't see shit with all the heat waves and smoke rising up. When I finished the 600th round the barrell was glowing red out to about 2 inches from the flash suppressor. It kept jamming the whole time.
Link Posted: 10/1/2004 4:32:18 AM EST
Remember seeing some videos of tests that the Army conducted to determine cook off with different weight barrels. Hence the development and adoption of the heavy bbl for SF.
Link Posted: 10/1/2004 6:03:06 AM EST

Originally Posted By woodrow1976:
My driver who was directly underneath the weapon said he could see rounds pass through the barrell. I couldn't see shit with all the heat waves and smoke rising up.



I heard that this could happen to M60s during extended shooting, but had dismissed it as legend, but I guess it's not.
Link Posted: 10/1/2004 6:12:46 AM EST

Originally Posted By m193:
Thanks. This confirms the story my Dad told me about the barrel drooping on his M16 in Vietnam. I had read many posts here that say the gas tube will melt before anything happens to the barrel, so I've never mentioned it before.
.



To be fair - CavArms did a bunch of shooting a couple of years ago (Full auto). They use the pic of the burst gas tube - but intact handguards, to show how tough thier product is.

Commercial gas tubes often WILL fail before the barrel. But if you have good quality parts (i.e. true mil-spec) it looks like the barrel will fail first.
Link Posted: 10/1/2004 7:54:28 AM EST

Originally Posted By Forest:

Originally Posted By m193:
Thanks. This confirms the story my Dad told me about the barrel drooping on his M16 in Vietnam. I had read many posts here that say the gas tube will melt before anything happens to the barrel, so I've never mentioned it before.
.



To be fair - CavArms did a bunch of shooting a couple of years ago (Full auto). They use the pic of the burst gas tube - but intact handguards, to show how tough thier product is.

Commercial gas tubes often WILL fail before the barrel. But if you have good quality parts (i.e. true mil-spec) it looks like the barrel will fail first.



Having disected cheap commercial gas tubes and quality gas tubes I can also verify that there is a HUGE difference in quality between the two.
Link Posted: 10/3/2004 1:50:03 AM EST
Link Posted: 10/3/2004 3:44:43 AM EST
I wonder if that was covered under the warranty?

Kharn
Link Posted: 10/3/2004 3:55:06 AM EST
[Last Edit: 10/3/2004 3:55:56 AM EST by gotm4]
IIRC this is one of the barrels that the US Army Rangers destroyed in their 'break contact' drills. I believe this led to the development of the heavier SOCOM M4 barrel and the H2 buffers. There is this same pic in The Black Rifle II.



Originally Posted By M4A2_L073754:
This might be one of those doomed M4 barrels... Found it from AR15.com couple of years ago.

MN


Link Posted: 10/3/2004 9:46:08 AM EST

Originally Posted By gotm4:
IIRC this is one of the barrels that the US Army Rangers destroyed in their 'break contact' drills. I believe this led to the development of the heavier SOCOM M4 barrel and the H2 buffers.



+1
Link Posted: 10/3/2004 10:45:49 AM EST
Maybe I shouldn't run my whole beta mag through as fast as I can pull the trigger! (unless, of course, I'm ready for a new upper)
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