Charging Handle is right on.
The ammo being tested by the military, and being used in Afghanistan as part of those tests, are NOT identical to the commercial loads we can get. In most cases, the military folks working on the project have selected commercial loads and then requested modifications to those loads to make them better suited for military use. These loads are all sealed and have crimped primers, and some have bullet cannalures, added by request.
Remember, too, that the goal of all this testing is to improve the performance out of the M4's 14.5" barrel, by finding loads that fragment at lower velocities, which means: out to longer distances. While these loads easily outperform M855 against humans, they don't outperform M193 by nearly as big a margin, though there is still some improvement.
The main reason why our "general recommendation" is still for M193 for US is because of the very limited availability and high cost of the newer loads. And while the somewhat-less-optimal civilian versions of some of these loads are more easily available, their cost is still 4 or 5 times as high as M193, again without a performance increase anywhere near that degree. M193, then, remains the best choice for ammo that is widely available, fully "militarized", works in ANY barrel twist, and is cost effective.
Having said that, there are certainly barrel configurations and scenarios where other loads besides M193 are better for the job. And, if everyone could buy case-quantities of the military loads of the 75gr ammo for not much more than M855 prices, we'd probably revise our recommendation. But we don't see that as being the case anytime soon. Remember, even the military is only in it's TESTING phase at this point.
-Troy