What's wrong with belt-fed AR15s?

Jenrick said:

Water cooled guns normally don't require pumps. The natural convection of the hot fluids, and condensing can take care of keeping the water moving, and the water jacket full. Unless you're talking pallets of ammunition like in WW1.

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In reference to the M1917, it contained 7 pints of water. Which is 1.25 pounds per pint. Almost 9 pounds water weight compared to the air cooled M1919 machine gun. Pump is either active or passive circulation. The M1917 manual suggests mixing antifreeze when the passive water pump (convection) was no longer effective. Maintaining a water cooled system is much more intense. ie "Joe" will break it.

http://www.big-red-one.org/FM 23-55 M1917 M1919 .30 CAL MACHINE GUN.pdf

I don't completely discount a water cooled crew served machine gun in the future. Gels, convection, all sorts of technology are getting better every year. Even just a gel cooled neck pillow is something that would not have been thought of in the 1920s. We are in a time where air cooled is the best we have right now.

I don’t like loading a stack of mags for an afternoon of fun shooting my AR’s... I can’t fathom how much I would hate assembling links and stuffing cartridges into them for an hours worth of fun... .

No, in all seriousness a belt fed AR sort of defeats what I think the purpose of the AR is: a lightweight, portable, accurate and ergonomic rifle that’s easy to carry, fire and reload.

(Now a Browning M-2 or M1917? THOSE would be cool toys!)

Stay safe.

Riomouse911 said:

I can’t fathom how much I would hate assembling links and stuffing cartridges into them for an hours worth of fun... .

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Trust me, its not fun. I have had to load Dillon minigun magazines linking 100 round belts designed for the M240. Those minigun mags hold 4,000 rounds and the GMV it was mounted on carried 3 mags, so do the math. Every time we had to do this, it involved the whole team sitting around linking together a mountain of M240 belts. Usually our minigun ammo came in 1600 round belts, but sometimes it didn't.

AlexanderA said:

The classic Browning machine guns (M1917, M1919, M2) were all closed bolt w/o quick change barrels. Yet that was one of the most successful designs of all time.

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Yep. I was trained on all 3 in the 80's when I was in the pipeline. These were very early MG designs; the M2 (the only one of the 3 remaining in service) has since been retrofitted to a QCB model.

herrwalther said:

Anytime we used the 249, the SAW gunners would get a few AR magazines. Gave the gunners some experience with non reliable method of ammo feeding.

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Believe it or not, the 3 SAWs that we had (before they were replaced by the MK46/MK48) fired reliably with the black HK416 mags when we tested them at the range. I tested them with both green tip (M855) and Black Hills 77 grain (MK262). Of course, these mags were only issued in SOCOM, and have since been replaced with PMAGS.

herrwalther said:

Anytime we used the 249, the SAW gunners would get a few AR magazines. Gave the gunners some experience with non reliable method of ammo feeding. I believe the non magazine models started filtering to line units after awhile but I was on my way out the door by then.

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The FN Minimi (what the 249 is based on) was belt fed, and the 249's been belt fed since Day 1.

The alternate magazine feed is only for "emergency" use.

AFA running an M16xx on sustained full auto, the closed bolt operation and fixed barrel are the disqualifiers. Gas tube
would hold up fine, but other stuff make it a no-go.

I don’t like loading a stack of mags for an afternoon of fun shooting my AR’s... I can’t fathom how much I would hate assembling links and stuffing cartridges into them for an hours worth of fun...

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It’s not that bad if you have a linker and shoot from one position, there are two things to pick up for every shot fired though, if you reuse components.

FL-NC said:

Believe it or not, the 3 SAWs that we had (before they were replaced by the MK46/MK48) fired reliably with the black HK416 mags when we tested them at the range. I tested them with both green tip (M855) and Black Hills 77 grain (MK262). Of course, these mags were only issued in SOCOM, and have since been replaced with PMAGS.

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Really? That is pretty interesting. Are the 416 magazines the molded polymer and built like the PMAGs? Only a handful of us were issued/bought PMAGs, so we didn't try them with the SAW. Line units started to compromise between issuing PMAGs to everyone or keeping the junk magazines. They issued Magpul 4 way followers to install into standard GI mags. Those certainly helped.

Steve762us said:

The FN Minimi (what the 249 is based on) was belt fed, and the 249's been belt fed since Day 1.

The alternate magazine feed is only for "emergency" use.

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I would prefer SAW gunners learn how unreliable magazines are in a controlled setting, and not a firefight. The SOP in one unit I was in required SAW gunners to have 2 M4 magazines either on their load bearing vest or in a 3 day bag for patrols. Most stuffed them in a bag, as our load vests had very few SOP rules.

jmorris said:

It’s not that bad if you have a linker and shoot from one position, there are two things to pick up for every shot fired though, if you reuse components.

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Ya, after a good day of semi-auto fun policing up the brass is bad enough...having to also have to collect up the belt links certainly would take a lot of the fun out of going to the range.

Stay safe.

herrwalther said:

The M249 is essentially a belt fed AR15, as far as weight and length go.

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Nowhere near the truth. FightLite's development of Shrike checks in under 10 lbs and SAW comes in at 18 lbs. That is precisely the reason why a belt-fed AR isn't going away, with all of its disadvantages regarding durability, cook-offs, and the like.

MTMilitiaman said:

This is why the Marines went with the M27 IAR, which is basically a Western M4 equivalent of the Soviet RPK. It fires from an open bolt on automatic fire and a closed bolt in semi-auto, giving it the ability to sustain automatic fire better than a normal closed bolt M4, but still retaining the accuracy of a rifle in semi-auto.

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The Marine Corps didn’t adopt the IAR until well after I got out, so I’ve never seen or handled one. But I’m fairly certain it’s exclusively closed-bolt, even in full-auto.

Theohazard said:

The Marine Corps didn’t adopt the IAR until well after I got out, so I’ve never seen or handled one. But I’m fairly certain it’s exclusively closed-bolt, even in full-auto.

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You're right, the requirement to fire automatic from an open bolt was dropped due to the complexity it added to the system.

herrwalther said:

No such thing as M4A4. Counter-Strike doesn't count...

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Well I've seen A4 uppers (removable carry handle, KAC RIS) on a lower with semi/3 round burst issued with Trijicon RCOs. They were just phasing out the M16A4 when I got out and replacing them with the M4. Don't know what you want to call it, but aside from a shorter barrel and gas system, and collapsible stock, it was identical to the M16A4, right down to the fire controls.

edwardware said:

I'm interested to know what one has to do to get near blowing a gas tube. Is this a high round count thing, or and extended mag(s) dump thing?

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I have seen plenty of gas tubes blown or melted with stunts like doing C-MAG (100 rounds) dumps full-auto or repeated and sustained full-auto fire with 30 round mags, until the gas tube failed and some in some cases the barrel failing. This usually occurs right by the FSB where the barrel enters the FSB.

Shoulder fired assault rifles and their like were never designed for sustained full auto fire. Anyone who has been trained properly knows full-auto is a "sometimes" feature used for ambushes, filling a hallway or street/alley to move the squad. Real shooters use semi and aim and use their optics/red dot, you can only carry so much ammo. A few mags is ok under certain circumstances, but its a lightweight shoulder fire air cooled weapon, NOT A WATER COOLED BELT FED MG .

Things like the Shrike/FightLite and other belt fed AR15/M16 are special pieces of kit for a skilled shooter that understands the platform. A semi- auto version may seem like a range toy to some, but remember we have goofy illogical gun laws(INFRINGEMENTS). A semi-auto belt fed AR with something like one of Geissele's triggers can get plenty of rounds off.


M4 vs. M4a1 carbine; destructive testing

Pondering on the drive home from work today. A belt fed, heavy barrel, AR-10 platform would actually have some serious pro's in the civilian world. Particularly with a 20 or longer bull/target weight barrel.

herrwalther said:

Are the 416 magazines the molded polymer and built like the PMAGs?

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This is what they looked like. I believe there are polymer mags out now for the 416- I'm talking about stuff I was issued long ago.Black, heavier, and a straighter profile than the standard US GI mags. We had good luck with them. The 416 has a different shaped mag well than a M4/M16 and the clones, so there are issues with using "standard" AR mags of all types in the 416, but these mags work fine in a M4/M16, etc. The downsides of these mags is that they are heavier than a GI mag or PMAG, and because of the different profile, they may not fit in issued MOLLE ammo pouches, depending on what company made the ammo pouch. I also heard anecdotes that these HK mags don't do great in salt water, but I never personally used any in such a scenario. I believe the UK uses them in that weird backwards rifle that they issue as well. I quit deploying as an "action guy" in '08, about that time PMAGS came on the scene. Since they were reliable and lighter than the HK mags, I think the HK mags have pretty much gone away. I still have a few HK mags buried in the shed somewhere.

Skylerbone said:

I thought the sole purpose was to work around magazine restriction States, though I can be naive about such things. If true however, it might make for an interesting project until some politician takes it to task to further restrict rights.

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This was my first thought too. “No 30 round magazines allowed?” Ok, this rifle has no magazine at all.