Jim Sullivan on the M16 in Vietnam

When I have the chance to interview Jim Sullivan, one of the original designers of the AR15, one of the subjects that came up (not surprisingly) was the record of failures of the M16 early in Vietnam. What was the cause of those problems? The full story includes several compounding issues, including a lack of issued cleaning kits and non-chrome-lined barrels. But most significant, according to Sullivan, was an inexplicable reformulation of the powder in the 5.56mm ammunition. This caused a huge increase in gas port pressure (in the order of 10,000 psi) and directly caused parts breakage and unreliable operation. Here is his description of the situation:

Jim Sullivan on the M16 in Vietnam








In an unrelated note, it has come to my attention that Apex Gun Parts has gotten their hands on a bunch of parts kits for Spanish CETME-L rifles. These were a domestic Spanish take on the H&K style roller-delayed action, in 5.56mm and using NATO standard mags. They were replaced by the G36, and there was speculation for a while about the possibility of getting kits into the US – well, Apex actually has them in hand now (sans receiver and barrel). It sounds like they have enough to make it worthwhile for parts manufacturers to develop semiauto parts and receiver flats for them (no parts are interchangeable with H&K rifles), so I already placed an order for one myself. The introductory price of $225 for a kit is pretty cheap for something that won’t come back again, and if the market develops a good build solution for them it will be a neat and unusual rifle to have!

CETME-L parts kit


  1. I’m sorry Ian, but the HK G3 and his derivares are all german take on spanish CETMEs,

    The CETME was a Ludwig Vorgrimler design, and was licenced to the west German Goverment

    • Yes, I realize that…I suppose my wording could have been better. What I was trying to get at was that Vorgrimler and the other German engineers engineers had long left Spain by the time the model L was designed and adopted, and they had developed and marketed a 5.56mm rifle through H&K (the HK33). The CETME-L was designed in the early 80s, and shared no parts compatibility with the HK33, despite being identical in concept. That’s what I meant by domestic Spanish.

  2. The 7th Cav would have used Colt XM16E1 at Ia Drang, not the 601 or 602, and certainly not original ArmaLite production.

    The propellant issue was far more complicated than the popular narrative supported by the Ichord Subcommittee. IMR 4475 was going to pose its own problems with excessive chamber pressure if DuPont had not withdrawn it as a qualified propellant for M193. Moreover, keeping IMR 4475 would not have solved the problems with chamber corrosion nor the non-existent case hardness standards.

  3. Oh boy, this rifle is so fugly that almost approaches beauty, in some really twisted way. Its like some of those mongrels stolen and then sold with forged pedigrees by the Good Soldier Sveik. It even beats the swiss Stgw 57. It almost deserves the Congressional Medal Of Ugly, the one poor private Joker never got. That being said, I would like to get my sweaty hands on one…

  4. The CETMES L , here in Spain , have a very bad reputation .

    The prototypes were very good , but the ultimate weapons due to budget cuts , had inferior materials , weak receivers , bad chargers , taking many interruptions ..

    The same thing happened with AMELI MG, which was even rejected by the English army when they arrived the first units

    As you say was replaced by the HK G36 , although still operational BY UNIT second line and some police forces and the Civil Guard.

    Civilian shooters have not had access to it , as the .223 is forbidden for civilians.

    I hope the kit fits you well , and prepare us a good video

    Thanks from Spain for your great web

    • I have heard about that. In retrospect, all that “German genius in Spanish pantalones” should have stopped with CETME/G3. Those are sound and decent rifles. With 5.56 conversion the reliability were rapidly down; this calibre is just not fit for roller-delayed blowback. I wonder why it had to take so long to recognize it.

      But now Spain had decent rifle, doesn’t it?

  5. During an extended stay in Spain over a decade ago, I still saw the 7.62mm CETME used by the Policía Nacional, and the CETME L 5.56mm used by various army and Guardia Civil while most troops already had the G36.

    We’ll have to see if an interesting stamped-U.S. receiver design can be developed to make use of the kits! Maybe the glitches can be worked out to some extent.

  6. Did you and Sullivan talk at all about the M16a2? Also, is any actual company interested in Sullivan’s tweaked ARs?

  7. The Cetme L assault rifles have a horrible reputation here in spain, ironicaly they were called the ”toy guns” like the M16 in Vietnam or the ”plastic cr*p”.
    The original design was good but cuts in production values made those guns nearly useless. This was the end of the independent spanish military smalls arms production, G36, wich is not wonderfull either (look a the recent comment from german soldiers) were made here but under license, of course.

    • Spain, along with Britain and France do not have domestic source for rifles…. you must wonder why. In any case, to be stuck with HK plastic wunder is not that bad; look what you have out there otherwise. Not much.

  8. I’m going to get one of those kit. I don’t have any Spanish guns and have been thinking I should have a delay roller lock rifle to study. I can kill 2 birds with one stone.

  9. Did anyone test the effect of similar cartridge pressure changes on other select fire battle rifles? Is the AR action more prone to that problem that the FAL/Roller locking H&K’s/AK/MAS-49/STG-44?

  10. Ian, I love these interviews with Jim Sullivan. I always like getting technical information first-hand, if possible. I’ve been burned too many times playing “telephone.” Thanks for reaching out to him and bringing us these great interviews.

  11. Escorted Colin Lienster of LIFE magazine to the Navy Hospital in Danang late 67–early 68 to interview wounded men about M16. Zero fans. Horror stories about malfunctions when they were REALLY inconvenient. Eventually they got better but the combat rollout was a Whiskey Tango Foxtrot moment

2 Trackbacks / Pingbacks

  1. SayUncle » But I read on the internet that AR-15 rifles are unreliable. It must be true
  2. More “M16 Failures” – 507th Maintenance | WeaponsMan

Leave a Reply

Your email address will not be published.