M4/M16 Fire to Destruction Test

[Bartholomew Roberts]

I happen to be in possession of a 1996 test where the M4A1 (older version without the upgrades) and the M16 were tested to the point of destruction. Since it became apparent in a recent thread on THR that a lot of people weren't aware of this information and/or don't spend much time reading the technical reports on this stuff, I thought I would repost some of the key elements here.

I have the full test (with badly reproduced black and white pictures) in PDF format; but it is 1.6MB and will not fit through THR's file attachments:

The test was published in September 1996 by Jeff Windham of the Small Arms Branch, Engineering Support Directorate, Rock Island Arsenal. The M4 was actually tested twice because the first M4 held up so well that they ran out of ammo to feed it before the barrel burst - so there are two sets of data for the M4.

The weapons were placed in a fixture with remote firing and remote operation of the charging handle. The weapons then had thermocouplers placed on them to measure the temperature. The weapons were then fired fully automatic for the entire magazine with magazine changes roughly every 10 seconds.

The M16A2 (modified to A3) fired 491 rounds in 2 minutes 49 seconds before it burst. There was noticeable drooping of the barrel and a noticeable change in the sound of the report prior to the barrel bursting. The barrel reached a maximum temperature of 1,599F and ruptured approximately 8 inches forward of the chamber.

The M4 in the first test fired 540 rounds in 3 minutes and while the barrel was noticeably bulged and a bit droopy; but it did not burst. A maximum temperature of 1,712F was reached on the barrel.

The second M4 fired 596 rounds in 3 minutes 32 seconds and reached a maximum temperature of 1,639F before bursting. The barrel burst approximately 4 inches in front of chamber.

The hypotheses from the test is that the greater muzzle weight/length of the M16A2 barrel contributed to its earlier failure as the barrels became hot and began to droop.

If anybody wants the PDF, you can email me and when I get around to it (which is unlikely to be soon), I will email you my copy of the PDF. The test is also available as AMSTA-AR-ES-92-2.

 

[praharin]

That is kind of interesting. I wouldn't mind a copy if you could e mail it to me at [email protected]

What was this test supposed to prove? I can't see any functional information gained from that test. If someone tried to hold an M4 with a 1700*F barrel there skin would melt off.

 

[rcmodel]

It was supposed to prove how long it would take in a firefight before your gun would melt. A hot hand-guard would probably not stop you if you were being over-run by communist hordes hell-bent on killing you!

Useful information for a GI combat rifle with full auto capability.

rc

 

[taliv]

excellent info, Bart. thanks for sharing.

I'll add that I was told in a carbine diagnostics class of similar tests performed at colt and based on their results they said it was roughly 130 rnds before rounds would start cooking off in the chamber, and 500-600 before the barrel would blow up.

 

[Blakenzy]

3 minutes of zombie-mowing time.

 

[LoneStarWings]

How would something like an Ma Deuce, M241, or M60 compare? Could they all fire off a few thousand at this pace before coming apart?

 

[Onmilo]

The main point of the test alluded to is that heavy barrels are desirable when using an infantry rifle in the role of a light machinegun.

Subsequent testing has shown a heavier profile barrel substantially increases the mean number of rounds before weapon failure.

Subsequent testing after this round showed that a burst limiter virtually eliminated barrel failure of the lighter government profile barrels as well as virtually eliminating the problem of chamber cook-off of live rounds in overheated barrels mainly due to the increased cooling cycles the burst limiter allowed.

Much of the meat of the test reports can be found in the Black Rifle books, volumes one and two.

 

[Z-Michigan]

I found the PDF online here:

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA317929&Location=U2&doc=GetTRDoc.pdf

 

[CYANIDEGENOCIDE]

The fundamental difference between the m-16 and the m-2 or 1919, or 240 saw is the belt-fed weapons are designed from the getgo to endure that sort of treatment. Heavier barrels, thicker receivers, some of the older stuff had a waterjacket. I would fully expect any weapon to fail at some point, but improvements can be made to stave off the inevitable.

 

[HorseSoldier]

+1 on machineguns being built to run more rounds faster than a carbine or rifle. Before their barrels burst you'd want to change barrels . . .

 

[praharin]

It was supposed to prove how long it would take in a firefight before your gun would melt. A hot hand-guard would probably not stop you if you were being over-run by communist hordes hell-bent on killing you!

I must admit that I have never been over run by any communist hordes. I still doubt that I would have to go cyclic with an M16 for over 500 rounds continuously.

 

[The Lone Haranguer]

Those barrel temperatures are

 

[Float Pilot]

HorseSoldier +1 on machineguns being built to run more rounds faster than a carbine or rifle. Before their barrels burst you'd want to change barrels . .

.

+2

During a shooting demonstration we intensionally linked up a 400 round belt for one of the newer M-249's (SAW) and fired all 400 rounds in one long burst with no stopping. While the barrel started to look an odd color, that SAW kept on shooting.

After a good cleaning I used the same SAW the next day, with the same barrel at 300 meters, shooting torso size pop-ups. Just to prove that the SAW will shoot when properly lubed and maintained, even with high round count abuse.

Way back, I did fire 14 thirty-round magazines through a M16A1 (Hydramatic made) in a fairly short period of time. Although I believe I was actually shooting rapid aimed semi-auto during most of that incident. I thought it was over a long period of time but another troop watching us from a nearby hill said it was all over with in two or three minutes. I do not remember changing magazines 13 times either. Anyway, that old A1 did just fine with that light barrel.

 

[SHvar]

Interesting, on a few occasions, 6 members of my old active duty unit fired 30 rd mags through our M16A2s while anywhere from 12 to 24 members of the unit loaded. The entire unit supplied mags, they were loaded until all 3000 rds were used, and fired. This was how we discovered there were 2 mags that were junk (good odds).
Not one rifle was damaged, not one melt down, and all 6 were accurate afterwards, these instances were in the spring and summer in the American south (very warm nice sunny days). These M-16A2s were fired on 3rd burst, and a few rds on semiauto, there was no wait between loading mags, or to allow them to cool down, or to switch rifles.
I was involved with this being done with AR-15s once, not one problem, keep in mind these were semiauto, so again much increased barrel cooling time.
I once saw an M-60 team link 900 blanks together on an island off the coast of Florida, they had a runaway while defending a building roof top with it, and fired all 900 blanks without damage (not sure if I can discuss what training was going on there). I wouldnt try that with live 7.62X51 rds.
I was amazed at how tough the M249 SAW barrel is, those things can be fired until the barrel glows almost white, and they keep going. I dont know the numbers of rounds that were fired, I was working the range, not night firing with them that day (I was a grenadier, not machine gunner).
I saw a few ARs fired with multiple Cmags until empty without issue, they were dumped fast, not fired slowly.
This test would not apply to semiauto ARs, the rate of fire is much lower and cooling time much increases the durability of the barrel. In fact this was why 3rd burst increases durability of the M-16A2 barrel over full auto (one of the original purposes for 3rd burst over full auto on the M-16A2, along with the heavy barrel).

 

[C-grunt]

When I was a new private, ie.. SAW gunner, in the Army in 03 we did a trench clearing live fire in Kuwait. I had 3 200 round drums for the SAW. My squad was the first ones in and set up a fire support/defensive position. My squad leader told me I had to shoot all my ammo before the platoon finished clearing the trench. I fired all 600 rounds in about 70-100 round bursts with only enough time in between to reacquire targets or switch drums. I probably shot all the rounds in less than 2 minutes. The SAW ran through it great and still worked fine after that.

 

[Z-Michigan]

Armalite (fka Eagle Arms) tech note on heat and reliability:

http://www.armalite.com/images/Tech...el Design, Heat, and Reliability, 030824….pdf

While this mostly discusses gas system length, it does have a paragraph on barrel temperature and metal strength.

 

[freakshow10mm]

In my testing, an M16 will have the barrel shot out within 6,000 rounds of full auto. Accuracy starts to deteriorate as well as throat.

 

[praharin]

barrel erosion compounds with heat. how fast was the 6,000 rounds fired on full auto? continuously? 100 rounds a day for 2 months? It makes a difference.

 

[Acera]

What 18 posts into this thread and no comments about how much better an AK would perform?? Come on guys, I know you are out there, tell how the AK would perform better. Good mother Russian steel is supposed to melt at twice the temp. as capitalist, lowest bidder, crap right?

 

[AgentAdam]

These must have been pencil thin barrels. I would expect 2,000-3,000s round of non stop full auto with a heavy or HBAR barrel before the gun started jamming to much from the cooked off bolt carrier to continue the test. I can't even imagine my Bushmaster m16 barrel drooping or bursting. It's nearly 1" thick under the hand guards. You can see AR torture test on YouTube going threw over 1000rounds in full auto for 15 minutes straight.

 

[Z-Michigan]

no comments about how much better an AK would perform

Maybe this group has moved past that age-old debate.

I can't even imagine my Bushmaster m16 barrel drooping or bursting. It's nearly 1" thick under the hand guards.

It sounds like your barrel is a civilian heavy barrel. A GI A2 type barrel is thinner under the handguards than it is past the gas block/sight base.

 

[musick]

What 18 posts into this thread and no comments about how much better an AK would perform??

Maybe this group has moved past that age-old debate.

Sorry to derail this thread, but that is the reason I joined this forum - overall it is the most mature firearm forum I have found. Not perfect, but very tolerable.

Let the horse RIP.

Back on topic: I dont see how that test reflects the real world. Both platforms are more than adequate.

 

[AgentAdam]

I have an civilian M16A3 as far as I'm concerned but yes it does have a "target" heavy barrel that despite the regular infantry setup is very thick under the hand guards. My M4 does taper back down to pencil thin under the hand guards but i don't consider it as an extended use heavy gunner weapon. I would still expect well over 1,000 rounds before the barrel popped.

 

[SHvar]

Here is the link to the POF torture test, and temps were below 800. 1036 rds with a single stoppage due to a damaged beta mag. Temps measured every 100 rds, fired full auto and better yet from a 9.25 inch barrel.

http://www.pof-usa.com/articles/P416Torture.pdf

 

[Bartholomew Roberts]

The Small Arms Review Test of the POF isn't really comparable to this test for a number of reasons:

1. The Rock Island test used thermocouplers to measure the temperature, meaning that it got both more accurate data and real time information on temperature not subject to the types of measurement errors that IR thermometers can cause.

2. The SAR test allowed about 90 seconds between magazine changes (which was necessary to measure everything with an IR thermometer). As a result, it took SAR about 3 minutes 30 seconds just to fire 300 rounds. This test had an effective rate of fire about twice of what was used in the SAR test.

3. The POF-416 used a heavy profile, fluted barrel (and not a 9.25" barrel; but a 16" barrel according to your article). These tests used a 20" A2 profile barrel and a 14.5" M4 profile barrel.

4. The POF used a free-floated, vented aluminium rail system. These typically aid cooling on a rifle. These tests used the M16A2 and M4 double-heat shield handguards.

However, there are some weird discrepancies in the SAR tests. For example, the SAR test recorded a maximum chamber temperature of 133F at 264 rounds in the direct-gas rifle, where in this test TC-1 (thermocoupler on the chamber) showed a heat over 1,000F by the end of the test and a temperature of about 300F at the first 30 round mag change and a temp of around 475F by 264 rounds. That is a pretty significant difference in temperature measurement between the two tests.