Shooters of the M-16/AR-15...have you ever experienced the "Vietnam Jam"?

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natedog

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I read something recently that when the first XM16E1s were being tested in Vietnam, they would experience failure to extract malfuctions.

The extractor would rip the rim of the case and the bolt would go back, leaving the fired case stuck in the chamber. Then, the bolt would move forward and lodge the next cartridge behind it. The only way to clear the malfunction was to eject the magazine, lock the bolt back, shake the gun until the unfired round fell free of the reciever, and then take a cleaning rod or similar object and ram the fired case out of the chamber.

Then, you'd reinsert the magazine, chamber a round, and resume firing. Apparently, the author of that article experienced these malfunctions first-hand as a Marine in Vietnam.

Has anyone here experienced this type of malfunction, wether using civilian AR-15s or military M-16s? Did adding a chrome lining to the chamber and changing the propellant to stick powder fix the problem?

Thanks for your input, and please don't turn this into an "AR-15 sucks, rifle xxxx is much better" thread. I'm looking for actual examples.
 
It sounds to me like it was the result of corroded/rusty chambers and very hot ammo. Chrome lining would solve it, as would cleaning and lubing the chamber properly but obviously, it would be difficult to keep up such maintenance in battle, in an incredibly hot/humid jungle.

Even today, Lake City M193 is very hot ammo. I wonder what the velocity differences were between M193 with ball powder and M193 with stick powder?
 
Well, no.

The Marine Corps gave me an M16 in 1970, when I was stationed on Okinawa. I only fired it a few times, for annual re-qualification.

I had been issued one in "IRT" (secondary phase of basic training) and Infantry School. Shot those a bit more, in various training excercises.

All the ammo I fired was issued to me by the Marine Corps, of course.

I do not remember a single 'ripped rim' in my time. I cannot remember if there were any other malfunctions... nothing that seared itself on my mind.
I don't think I've even seen one by one of my colleages.

Natedog, the malfunction you cite is legendary. I've heard of it often. It must have happened somewhere. But not to me.

Just for the talley books, I'm not a big M-16 fan. Neither the design nor the cartridge.
 
Actually yes I have...multiple times. I have a DPMS lower and Model 1 upper...chrome lined bore and chamber. Squeaky clean.

With any other ammo I've tried I don't have this problem but with Santa Barbara (Spanish) SS109 NATO surplus, I get this EXACT problem about 1x per mag.

Examination of the case (once I've run a brass rod down the barrel to dislodge it) is that the rim is severely gouged out by the extractor. I put a #60 o-ring around the extractor spring to increase the extractor force...that just results in it ripping the rim off with more force.

I'm guessing that this has to do with potentially softer brass used in the Spanish ammo and maybe a slightly out of spec chamber? That would explain it sticking to the chamber (chrome lined remember) and having the rim ripped off. The gun seems to do it whether it is clean or dirty. Has never happened with any other brass cartridges I've run through and certainly doesn't happen with the Wolf I shoot for plinking.
 
I've had one torn rim from a cartridge that I suspect was from weak brass, it was in one of my AR15s and it's the only one I've experienced in somewhere to the tune of 4k+ rounds of ammo.
 
No... but it is known to happen.

Early Vietnam guns with their combo of no chrome lining/wrong powder/incredibly humid climate were more likely to have it happen.

IIRC, its usually an indication of over-pressure ammo. IE, the case is still expanded up against the chamber walls so hard when the action starts to cycle, that even the extractor ripping the rim off the cartridge will not extract it. Chrome lining is more "slick" and much less suseptible to fouling in humid climates than non-chrome, which is why the chrome chamber makes a difference.

I've never had it happen with any ammo I've tried.
 
That sounds to me like a brass problem... I mean, how is the action at fault if the rim of the round actually rips off?

I've never noticed any markings at all from my BM using Q3131A or Wolf ammo, and the white box is pretty hot stuff (well it feels like it).

Maybe an extractor with a larger surface area would be better? :confused:

Sounds more like a tight chamber/soft brass problem to me.
 
8 years active and even an armorer for a while, never saw one, the only issues I have ever had in the civ world was a DPMS low pro upper that had a match chamber, it hated coated cases like wolf but would shoot good brass all day long.
 
I just asked my dad a few seconds ago about this and he had a M14 when he deployed there, then later switched the M16, and then the M16A1. According to him the original M16 and A1 had no problems of that sort whatever, and "the only jam I ever had was with an A2" which would be in the mid 80s, or when he was in the Gulf War.
He also said he preferred the the 16 to the 16A1.
 
This did happen some and unfortunately some our men’s lives were lost with the early rifles in Vietnam. I believe the main problem was the calcium carbonate in the ball powder that caused the fouling once it was changed the fouling went away. The military still uses ball powder. Also if I remember right the buffer was changed to lower the rate of fire and the chrome chamber.

I think there is a Vietnam Vet on the board who was an armourer with the Marines and he saw a lot of these jammed rifles

When I went to RVN I had heard all the horror stories of the jamming and had some guys tell me how to thread a cleaning rod form the carrying handle to an M-60 belt clip snapped to my barrel. Funny thing was all the stories I heard were always second hand.

Once in my unit the old timers said I didn’t need the cleaning rod, as there wasn’t a problem.

I've had a SP1 since 1972 and a few years back I put a couple thoushand rounds through it without cleaning and it never misfired and I might add it was really dirty.

In country 68-69 I was a rifleman one-day then took over as an M-60 gunner for the next four months. When I made squad leader I got the 16 back. The most rounds I ever put through my 16 at one time were 12-14 mags. (20 round loaded with 18 rounds) in firefight. The rifle never missed a beat.

I have never had or seen or heard of an M-16A1 misfire, fail to extract etc. in combat (my unit).

I have great confidence in the M-16A shooting M-193 ball ammo. If you ever had to hump up and down the mountains in the Central Highlands of Vietnam you’d know why I also like the 16 for its lightweight including the ammo.

I don’t like the shorter barrel weapons M-4.

I you were one of the soldiers that had the problem I’m quite sure you would have a negative feelings told the 16.

Have a good day and remember to pray for our troops around the world.

Turk
 
In the military: No, and I didn't see it happen to anyone else.
As a civilain (I own 12 AR15s): No
In the three carbine classes I have taken: No
 
Grendelizer, thanks. Great link.

All the stories I had heard (discounting second-, third-hand and so on) were from leaving the gun chambered for a long time in the humidity, and only in the pre-chrome plated era. Especially common among people like SPs on patrol all night with a loaded rifle. Some of them supposedly took to carrying chamber empty in an attempt to prevent sticking.
 
No. but I did have a M-1 that would do that like clockwork with surplus german M-2 clone ammo. new edjector cured that though.
 
Not with an AR or M-16, no.
But I did have it happen repeatedly with an AK type rifle.
It was a Norinco BWK something, bought it in the summer of '94, chambered in 5.56.
That thing would rip cases in half and stick the remaining part in the chamber like glue.
I took it back with 2 cases mashed into the chamber like they were welded and the shop gave me a 5.56 NHM-90 instead.
I miss those guns.
 
You need one of these:

http://www.buffertech.com/dfender.htm

dfender3.jpg


D-Fender2.jpg
 
I think that if you are ripping rims off cases, the extractor is doing its job, and something else (most likely the ammo) isn't.
 
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