We’re not really feeling it for a technical post this morning, so instead let’s introduce Andrew, a self-described “gun nut” and the personable host of the one-year-old GY6 Slo Mo video channel. Here is a loooong burst with a gun that solves a problem nobody has, a belt-fed full-auto AR in 9 x 19 mm.

This isn’t especially practical. If there’s something that needs a whole belt of 9mm at point-blank range, you fight it, we’re backing off and calling a fire mission. But it looks like fun and that’s reason enough to own a gun.

Actually, if you are interested in the Freedom Arms FM-9 belt-fed upper, he has a 20 minute full review, that answers pretty well “what it is,” without going deep into “what it’s for.” The quick-change barrel system (enabled by the gun being a simple mass-locked blowback) is clever and good.

We don’t think we want one, but we do think we understand it after Andrew’s video.

The feed mechanism is the now-customary MG-42 based design. Our guess, without examining the weapon, is that the reason that Freedom Ordnance wants you to load the belt with the feed tray cover down, and not up (mentioned at about 6:45 and 8:45), is because closing the feed tray with the bolt forward can damage the mechanism. It’s possible to design a feed system that can be safely close bolt-forward or -back — FN’s world-market machine guns are designed that way, by having a spring-loaded roller. 

These videos are quite unscientific, but they’re entertaining. Entertainment is an interesting use for high-speed photography that was developed for scientific and industrial purposes. (And, he makes it clear, he’s not trying to be scientific).

Don’t expect any great revelations from the shot-in-the-head videos. A 9mm kills Casualty Carl dead. Supersonic rifle rounds will usually produce an avulsed (evulsed?) cerebrum in Homo sapiens and will probably result in the catastrophic structural failure of Casualty Carl’s coconut skull… killing him dead. A .22 LR from a pocket pistol will break up the skull less, but will probably still kill Casualty Carl dead. In real life, humans have survived and recovered (more or less) from gruesome, close-range cranial wounds with all these weapons, but the odds are a head shot that’s a square hit has taken the recipient out of the fight for the immediate future.

Hat tip, The Gun Feed.

This entry was posted in Weapons Education, Weapons Usage and Employment on by Hognose.

About Hognose

Former Special Forces 11B2S, later 18B, weapons man. (Also served in intelligence and operations jobs in SF).

15 thoughts on “Slo-Mo Mayhem


“Avulsed” is the correct form of the verb.

E.G.: “That belt-fed 9mm sure avulsed the cash right out of that guy’s wallet, but what a splendid way to convert cash into noise and grins.”


Belt-fed 9mm: when you need to suppress the s**t out of the guy just down the hall.

Trone Abeetin

I’m sure LAV thinks that imitation is the sincerest form of flattery


What he said. A very efficient way to convert cash into noise and confetti. Would not want one for myself, but would be happy to pony up some coin of the realm to shoot a full belt. I am a relative FNG here, so likely you have covered this already—


Still, having repaired many a Pig as a 45B, I find it impressive.


Do you have a post in the archives on the MG42 feed mechanism? I have always been curious how all those rounds get fed so quickly – must be a nice piece of mechanical engineering.

Hognose Post author

The FN-MAG and M60 feed trays are copies, the M60 a little degraded and the MAG a little improved. On the US M240, Ordnance insisted on an M60 style “close only with bolt open” feed tray.


M240’s roller is spring loaded and the cover can be closed on a closed bolt.

The Air Force actually has a condition ‘Half-Loaded’ that has the bolt closed and ammo belt in the feed tray with the cover locked down.

Ordnance may have originally wanted a design of roller/feed tray that necessitated the bolt be locked to the rear, but that apparently didn’t last long as I never saw one in the inventory.


During WWII the Army tasked Saginaw Steering Division of GM with building 2 copies of the German MG42 in the standard US .30-06 Caliber. Somebody goofed, and the resulting toolroom gun would have worked all right in their original 7,92x57mm Mauser chambering, but were too short to complete the extraction/ejection cycle with the .30-06/ 7,62×61 ammunition. Ten years later, the T44/7,62x51mm cartridge was in development, and it’s probable that the T24s would have worked with that new round. One example, Number 9693 is [or was] still in the Springfield Armory collection, and the other, also from Springfield by way of APG, was for a while at least not too far from NWSC Crane in Indiana in the 1970s.


Happily, the folks at *Forgotten Weapons* have archived the .pdf *here* http://www.forgottenweapons.com/wp-content/uploads/2010/12/t24%20report.pdf

and it’ll give you some idea of what does what inside there.

The video *here*


is also instructive.

If you really want something happy to consider, note that shortly after WWII, the Finns considered building a MG42 derived-copy in their 7,62x53mmR version of the M1891 Nosin-Nagant rifle cartridge, using a Maxim/Goryunov type rear-pull feed belt. I’d to know how they were planning on doing that. But along came the PK, and that was that.


I actually have some illustrations of Aimo Lahti’s solution which apparently did work.

Alas while I’m great at archiving prodigious amounts of potentially useful information my organizational skills are at best out to lunch most days.

I’ll start digging and if I find the materials before the sun burns out I’ll forward them to hognose.


Well in defense of the belt fed 9mm the Austro-Hungarians cooked one up. Although seeing as how it never made it beyond a prototype and there is no Austria-Hungary anymore maybe not the best endorsement. Haha

But i think its pretty fun looking. every one likes a belt fed and at least this way ammo wouldn’t be expensive.


Having one of these in my hands currently, I can say with 100% certainty that you’re correct about the need to have the roller fall into the cam channel. That is indeed the reason the bolt either needs to be locked to the rear with the hold open, or the belt needs to be loaded on a closed cover.

Hognose Post author

Ok, that’s what I thought, thanks for the double-check. But if Miles says the US 240 retained the MAGs spring-loaded roller, then he’s right. Big Army always fought SF on having current GPMGs on the MTOE, we were more likely to have MAGs or MG42s, justified as being for foreign weapons training, than 240s for most of my career. And Aberdeen always tried hard to prevent us from live-firing the foreign and obsolete weapons.


I was specifically referring to the FM-9. It’s the older type of cover and roller design where it must have the bolt open to prevent damage to the cam channel, which is quite an oversight on a closed-bolt semi-auto! It’s still loads of cheap, low-recoil fun, though!


I think that could have a practical use w a “sub-lethal” type ammo for say “riot control”. Maybe a pepper round or something. Unlike a paintball gun, you change ammo and now it’s throwing lead.

I wanna see 6.5 x 52 carcano In The Face by the way.


There’s actually been a surprising amount of pistol caliber belt feds dating back to the early Thompson persuader of which at least a few prototypes were built.

Then there’s at least two Russian 7.62 tokarev belt feds as well as a smattering of others.