M4 Antics

There’s always been a lot of debate over the M4 carbine, and whether it should be replaced or what can be done to improve it.

One of the complaints is that it overheats after firing several magazines of rounds.

Turns out, Colt and the Army are taking a look at that issue. The carbine that most troops carry is the M4. The M4 can fire either semi-automatically, or in 3 round bursts. But the M4 also comes in the M4A1 version, that can fire either semi-automatically, or in a full-auto mode. The M4A1 is issued to special operations forces. One difference between the two variants is that the A1 has a somewhat heavier barrel to cope with the heat stresses of automatic fire.

What happens when you fire a lot of ammo through an M4 very rapidly? Take a look.  Colt modified an M4 to fire full auto, then put it through a stress test to destruction. I’m frankly a little surprised it failed that fast.

It looks like new production M4’s will feature the heavier barrel of the M4A1, but whether they will retrofit the heavier barrel to existing carbines is an open question.

In my own humble experience, I fired 7 30-round magazines on full auto through an M16A1 (with its notoriously light barrel) and it was getting kinda glow-y. And the handguards were smoking. And the gas tube was white hot. But the barrel didn’t rupture. Then again, I was shooting the relatively anemic M193 round, not the heavier M855.

Anybody else out there ever have a barrel problem with an M16/M4?

H/T: Lex

27 thoughts on “M4 Antics”

    1. I know I’m getting into this one a little late, but re: Brown Bess … she was introduced first in 1720. She was the standard issue weapon of the British Army for over a century. Bess continued to serve as the standard issue weapon of one army or another until the 1880’s or -90’s. I’ve heard anecdotal evidence that she still turns up from time to time today in the Khyber Pass. I don’t know if it’s true or not, but it wouldn’t surprise me a bit.

      So, Brown Bess certainly was good for quite a few wars.

  1. RC, I’m hearing about the High Reliability Parts Kit (HRPK) but haven’t bothered to look up what is in it.

    As for how long can we keep using the various models of the EBR (evil black rifle), I don’t know. Right now, we’re at 43 years of some variant of the rifle as the standard, which I think is pretty much a record.

  2. I’m just guessing, but I think some variant of the Browning .50cal will be around for a long, long time. Will the M2 we all know and love be in use? Maybe not, but the various successors, such as the M3M are more evolutions of it than true successors.

    I’m thinking the AR platform, especially the direct impingement mode, is going to be somewhat less long lived. Now, a gas piston version might have another couple decades left.

  3. Brad,

    You called it. The direct impingement is a huge problem. Civilian versions of both the AR15 and M4 have been built with gas pistons in the last few years. (Direct impingement puts the heat of the gases at the bolt key/chamber, precisely where you don’t want it.)

    I would like to see the M4/M16 design in 6.8mm SPC or similar caliber. A heavier, 110-120-grain bullet at 2800 fps, thereabouts. Lots more lethality, and the casings are the same size as the M855, so the bolt, extractor, chamber, etc, can remain the same.

  4. URR, that’s one argument about direct impingement that I’m not sold on. The gas hits the flange at the rear of the bolt, and is then vented through the bolt carrier. It never strikes the bolt face or chamber. In the linked video, it was the barrel that failed, not the gas system. I almost never had any carbon on the bolt face or lugs of my weapon. And in all my years, I never had a malfunction that wasn’t directly attributable to the magazine (except with FN built weapons- they were ALL crap).

    I said I think DI will go away. I don’t necessarily think it is the problem. The real problem is the Army wants a very lightweight carbine, and then wants to fire hundreds and hundreds of rounds through them. You can’t. It’s physics.

    And while I’d probably like to see a 6.8mm round, that would in fact just make the durability problem worse.

  5. The DI vents gas and heat, but not sure the amount of carbon is significant if the weapon is well-maintained. But the heat buildup is a problem.

    The 6.8 would require a heavier barrel, though chamber pressure would remain well below MAP, in fact, rise only so slightly.

    Roger on the idea of a light weapon with gargantuan rates of fire. It is like trying to find a tall midget.

  6. I love me some M-14, but:

    1. You ain’t getting a lot of automatic fires out of one.

    2. It’s big and heavy.

    And don’t forget, when the M-14 was first introduced, it was a disaster. The QC at Springfield was terrible, and the rifles were just about useless. It was just about the biggest scandal in American small arms history. But no one ever remembers that. They just bitch about the M16.

  7. Don’t need auto fire from my fire team. That is what the AR man is for. And I could envision an M-14-type weapon in 6.8, too.

    Yes, the initial run of M-14s was a disaster. But it was quickly fixed. One thing it never lacked for is hitting power. Whereas the M16A2 is a fine, reliable, accurate service rifle, but it still lacks hitting power. With the heavier 77-gr and 90-gr ammo, the life expectancy of the barrel drops precipitously.

    There ain’t nothing I can see that I can’t hit with an M-14. 147-grn boat-tail 7.62×51.

  8. The fact of the matter is, we aren’t going to see the M-14 re-adopted as the standard rifle. And some level of auto-fire is going to remain on whatever the standard rifle is (probably 3 round burst).

    Will the service ever go to 6.8mm? I doubt it. In a perfect world, I’d do a lot of things different than what they are now. Some you’d like, some you wouldn’t.

    But overall, the 5.56mm M855 isn’t a really bad round. We talk about hitting power, and how if it doesn’t hit bone, it doesn’t stop. But that’s fairly true of ANY round short of a .50cal. And we STILL seem to be able to zap a fair number of bad guys, as much as people complain about it.

  9. Surprising number of M-14s showed up in Iraq during my time there, and they were adored by their owners.

    And we will have to agree to disagree on the M855 62-grain round. It is a varmint round.

  10. Oh, I know the M14 made something of a renaissance in Iraq (and surprisingly, to a lesser extent, in A-stan, where its greater range would be more useful).

    Don’t like the M855? Wanna go back to the M193?

  11. The Army will NOT adopt 6.8 until the wars in Iraq and A-Stan are over. The logistics of switching calibers now would be nightmare fuel.

    I haven’t been depolyed, but I have had to clean M-16s with carbon on the bolt, trigger group, buffer springs and one weapon an LT pawned off on me to clean.
    Her Rifle was so dirty that the firing pin *oozed* out of the bolt, solid black until I spent 5 mins on it.

    The M-16/M-4 is the army tires to have it is the dog’s breakfast. DI makes for a dirty weapon, CLP attracts sand. In ADA land, our M-16’s are old. They double feed, fail to extract and don’t like to be anything other than white glove clean. Blanks? I curse the idiot who thought that crimping 5.56 cartridges was a good idea. Our magazines are old and love to fail at the wrost times.

    A piston system would make things easier, I wouldn’t have to spend so much time cleaning my weapon. I’ve seen double feeds that would be easier to fix with a piston system.

    Better mags are a fix long over due. Plastic mags are toys fit for Spec Ops and the local PD. I hear that cold makes them shatter.

    The NYT article talks about the increase in weight from a heavier barrel.

    To that I say: MORE PT! So what if a heavy barrel or a piston system adds 5,6,7 or 8 ounces.

    Ditch the lighter barrels and DI. heavy barrels and a gas piston system is the way to go.

  12. I think that lightweight but super reliable carbine you can run hundreds and hundreds of rounds through will be possible in a couple decades. At the rate that material science is advancing, I’d bet a paycheck on it.

  13. I wouldn’t. Dude, we’re talking grunts here. If you lock a grunt and an anvil in a padded room for an hour, when you come back, the anvil will either be missing or broke.

  14. Brad, you stole my line. Mine was actually a room with two bowling balls. Broke one, lost the other.

    Used to describe recruits. Drill Instructors are the funniest people on the planet.

  15. Grunts are the funniest. That or we spend so much time in miserable circumstances, all you can do is laugh or cry, and there’s no crying in baseball or infantry.

  16. And NO, I don’t wanna go back to the M193! From a varmint round (M855) to a small varmint round(M193)!

  17. What about the H&K 416, which apparently, Delta has been using since 2004. I thought I read somewhere, that eventually, the 416 was to replace the current M4/M16A2 etc as the standard issue weapon. Of course, thats very doubtful now, with these commie clowns in office. Whats the barrel specs for the 416? I don’t know.

    1. The H&K 416 is a superior weapon to the M4/M16A2.
      We should adopt that and forget about the SCAR or anything else.

  18. The 416 isn’t going to get adopted service-wide without a competition. Congress is already pissed at the way the Army went to the M4 in dribs and drabs without a competition.

    And if there’s a competition, Congress will write the rules for the competition. In which case, being better will have nothing to do with who wins.

  19. Congress tired that once. Some congress critters were pissed that the Army was thinking about replacing the M-16 back int he 80’s, going with that HK-11 and caseless ammo.

    How dare they take away US jobs!

    So Congress re-wrote the rules to say the the weapon must be 50% better than the M-16.

    They army dropped the Hk-11 for many reasons, but congress just put the final nail in the coffin.

    Funny how things work out 2 decades later.

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