Caliber/cartridge for .223 successor

[Herodotus]

This business of worring about having ammo that is only available in limited quantities for you own troops is self defeating.
The reason that NATO and the Warsaw Pact standardized their ammo was that such a policy allows the controling major power to raise armies of millions and millions of men on the shortest notice, both from its own resources and from any allies that may be available. This is really what would win any important war
You should not worry so much about what guerillas are going to do. Look to the big picture.
Colonial governments like the British used to worry about such things. The British outlawed all 45 caliber cartridges in most of Africa when a few of their own military rifles were captured by the Sudanese (?). Then they tried to make as many hurdles as possible to any subject of the Empire owning .303 caliber weapons and ammo for exactly the reasons you give above. They wanted to make it very hard for any potentially disgruntled subject fo get ammo in what they considered military calibers. All this backfired in their own faces when the real wars came along. They had just cut their own throats and could not arm their own men, much less arm their allies.
You will do the same if you go down this path. In a real crisis, millions will flock to our banner and so much the better if they can use our weapons and ammo.

 

[Solitar]

Herodotus

You just described a patriotic reason for the US Military and patriots nationwide to standardize on the .223. But you also described what the Feds are trying to do to the general public and patriotic individuals and groups - i.e. outlaw ownership of "military" weapons and ammo.

 

[Kernel]

6mm SAW - "the best cartridge that never was"

6mm SAW & .223

The Army has already spent the better part of a decade, thousands of man-hours, and millions of dollars developing the ultimate small arm cartridge. It's sitting on the self ready to go but will probably never be adopted because of political and economic reasons. It's not the biggest, the fastest, or a magnum anything. It's a compromise of size, shape, weight, function, recoil, and energy. Perhaps the perfect compromise.

It's called the 6mm SAW - "the best cartridge that never was". It was developed in the early 70's and is officially known as the XM732 BALL. It was intended to be used with the (then experimental) Squad Automatic Weapon. SMALL ARMS OF THE WORLD, 12th Edition, by Ezell mentions the 6mm SAW briefly as it covers the development of the SAW machinegun in some detail.

The 6mm SAW was not derived from 5.56x45 or the 7.62x51 (or any other cartridge case for that matter), it's case dimensions were totally unique. According to CARTRIDGES OF THE WORLD, 8th Edition, by Barnes the OAL of a loaded round was 2.580". The case had a .410" head dia. and was 1.779" long. It was loaded with an extremely streamlined 105 gr bullet that moved out at 2520 fps from an 18" barrel, not that far behind cartridges like the .243 Winchester and 6mm Remington.

It wasn't just a pie-in-the-sky project. Development got pretty far, a lot of ammunition was even loaded in bulk at military arsenals. You might even turn one up at a big gun show if you scrounge around the cartridge collectors' tables. $5 a round last time I saw one.

One interesting facts about the 6mm SAW is it was the first cartridge to be designed by computer. The technique called "parametric design" was a complicated model of complex thermodynamic equations. The Army wasn't that impressed and once they figured out how to make tracers work in .223 caliber bullets they dropped the 6mm SAW. To bad in my opinion, the 6mm SAW had a lot going for it, and in civilian form the brass would have been the basis for many, many interesting cartridges that never will be. -- Kernel

 

[NicMk5]

6mm saw ballistics

I ran a comparison of the 6mm saw(using the 107 grain sierra matchking data bc=.527)vs. 7.62nato, 5.56nato and a 6mm 87gr Hornady at 2900fps. The 6mm saw looks excellent as far as wind drift and energy go and good as far bullet drop.
However I like to have more velocity in a round. I think a wound from such a slow round would be a lot like 7.62x39. The 87 grain BTHP(this bullet is not designed for expansion) at 2900 fps might be more effective and it has less drop (111 vs. 132 at 600 yards).

 

[Badger Arms]

Nightcrawler: Caseless IS a quantum leap. You cite a single example of caseless ammo that never made it to production beyond prototype batches. In truth, a caseless round that duplicates the 5.56 would still offer enough advantages if properly executed to warrant a switch. You save the weight of the case and the step of extraction is eliminated. There are disadvantages that currently prevent fielding but so there was with rifles when they first came out. These things take time.