Tuesday, November 8, 2011

Boffins create a 7 pound machine gun

Not an "assault carbine", but a full, belt fed 7.4 pound machine gun.  And plastic cased ammo for it that is light enough so that every infantryman can be a machine gunner.

El Reg gives us the skinny:

But US military boffins at the famous Picatinny Arsenal have been working on this situation for some time. Since ammo weight and bulk is much of the problem, they have come up with a new kind of ammunition: Cased Telescoped cartridges.

In a cased telescoped round, the bullet is no longer attached to the tip of a brass case full of propellant powder. The new case is shorter, fatter and made of plastic, so weighing substantially less, and the bullet is sunk into the middle of the propellant which makes the whole round shorter - it has been "telescoped". A shorter round weighs less itself, and also means that the gun's action, feed equipment etc is smaller and thus lighter as well. It's a trick originally developed for tanks, to make the turret smaller and easier to protect.

According to the Picatinny scientists, their new LMG and a thousand rounds of its plastic-cased-telescoped ammo weigh no less than 20.4 pounds less than the current M249 (a version of which is also used by British troops) and a thousand ordinary 5.56mm brass cartridges. The new LMG shaves no less than 8.3 pounds off the 15.7-lb M249, coming in at just 7.4lb - actually lighter than a standard British SA80 assault rifle! This, perhaps, explains Specialist Smith's opinion that it would be reasonable for all soldiers to carry such weapons, rather than just heavy-weapons specialists.
This brings to mind the Garand, and why it's chambered in .30-06.  A 6.5mm round would probably been better - adequate stopping power combined with lighter weight.  But the Army had millions of rounds in .30-06 in warehouses, and so the Garand was designed for that caliber.

Shifting from the poodle-shooter 5.56mm NATO round to either the plastic cased telescope round (or better yet to fully caseless - if they can make it work) would mean cheap ammo for all of us, but a big expense for the Army.  And so technical committees will meet for years, tests will be run, and no decision will be made.

And Our Guys will have to hump heavier, less capable weapons into harm's way.  Some may die because of it.  Too much of the military works like this:
Two privates are on latrine detail, sweeping up soiled bits of toilet paper around the latrines. Just as they get all the bits swept up into a pile for collection, a gust of wind grabs one piece and sends it swirling into the camp, high above the heads of both soldiers. To their horror, it goes right in the window of the Colonel's office.

One soldier says to the other," I'll go in and get it, the old man is short sighted, half-deaf and naps a lot. I should be fine."

So off he goes, slipping quietly into the Colonel's office. He comes back a minute later, shaking his head.

"Well, did you get it?" says the first soldier.

"No" the second sighs," I was too late. The old man had already signed it."
Yeah, it's an old joke.  I'm only laughing on the outside.


Anonymous said...

Hmmm, plastic cases, huh.

I wonder if they still provide all the normal functions of a brass case, including sealing the chamber under those pressures.

Borepatch said...

I was skeptical too. But the video shows it in action.

Caseless ammunition is even more problematic. It's obviously lighter, but the technical aspects of sealing the chamber are interesting.

But if you could get it to work, you don't need the extractor/ejector.

But you don't need caseless for this.

Old NFO said...

Interesting technology... And sadly, I have to agree with you that it will take 20 years to get approval...

New Jovian Thunderbolt said...

"Surplus ammo from US stockpiles sold to US civilians? We haven't done that since 1995!" - Gen. Hapablap

Anonymous said...

What I am curious about is how easy it would be to remove the round from the chamber if there's an ammo related failure to fire. Ammo that can handle malfunction reduction techniques matters.

In caseless ammo, I don't see that it can be done at all and that makes me very wary.


Anonymous said...

It would seem that there are three problems to deal with caseless ammo:

1. How to seal the chamber in a relatively simple way that also allows for thousands of rounds before the most fragile part(s) of the mechanism must be replaced, and

2. How to ignite the propellant and ensure that it does not prematurely ignite after a while, and

3. How to easily clear a mis-fired cartridge under stressful conditions.

Firehand said...

I always wondered about the "We have all this .30-06, so we're not changing" argument; especially since, shortly after, they decided "We need a carbine for support troops" and created a new weapon and cartridge anyway.

Of course, from what I've read they didn't like the original Garand design because of the box magazine sticking out the bottom as well as the new cartridge...

Tam said...


For some of the skinny on the Marine's adoption of the IAR, read this thread. Pay special attention to comments by poster "Failure2Stop", as he has better inside info on the USMC's IAR program than any thousand random armchair internet Counterstrike kiddies.