Warning: I'm going to step on a few toes with this one because of my stance on the Second Amendment and my perpetual irritation with government intrusion on those grounds. I have nothing against those who disagree even if I think you're wrong.
Anyway, I guess it was bound to happen soon or later, but Obama is expected to sign an executive order banning the sale of surplus 5.56 under the guise of police safety because of its "armor-penetrating capabilities."
Well, I hate to point it out to him, but most rifle cartridges are considered to armor-penetrating because of projectile weight and velocity. This all started on or around the 15th of this month when the ATF (well, BATFE, or whatever their flavor-of-the-month acronym happens to be) decided that certain 5.56 rounds had no use in hunting or sporting. I think that's wrong, because a large number of competitive shooters have been acquiring the 5.56 surplus because it's cheaper. Supposedly, the ATF had established an open comment period until March 15th for the public to weigh in. I guess the President didn't get the memo...
While I'm disappointed about this, I'm not overly upset. I only have one rifle chambered for .223, and I don't make it a habit to buy surplus ammunition. I do think this is overreaching and unnecessary; if you want to protect police the police force, you probably ought to 1) stop militarizing them and 2) stop demonizing them (or fire Al Sharpton... that would do more good than banning anything that goes "bang"). What does worry me is that this demonstrates the president's "prosecutorial discretion" may be sufficiently misguided that his office believes they can use this to ban other types of ammunition, depending on the ATF's recommendations.
Incidentally, according to the FBI's own statistics, out of the 13,000 or so annual gun-related deaths in the US, only about 700 are the result of rifles, and most of those are from accidental discharges or hunting accidents. AR-15s account for surprisingly few considering the platform's popularity. But hey, who needs statistics when you have emotion?
For the uninitiated, 5.56 is the same as .223--to an extent. 5.56 being a standardized NATO round is describe in terms of metric measurements, and so the cartridge parameters are slightly different. 5.56 brass is usually a bit thicker than .223 and NATO requires the pressures to be somewhat higher in order to obtain the needed velocities. Generally, both rounds are interchangeable, though you should always be cautious and be aware of the differences.