.223 Rem chamber is tight, and gives good accuracy. Don't continuously run higher-pressured 5.56 NATO through it... 5.56 NATO chamber is not quite as tight as a .223 Rem chamber, and it can handle a wide variety of loads, both .223 Rem and 5.56 NATO. It's not as accurate (traditionally speaking) as a .223 Rem chamber. .223 Wylde is the best of both worlds, to some extent. You can safely shoot both types, .223 Rem and 5.56 NATO, and it gives a little better accuracy than a standard 5.56 NATO chamber. Go for the Wylde chamber, brother. <thumbsup> That 16" foliage gun that your wife took over at the range was a Wilson-Nordic .223 Wylde, midlength gas, 1:8 twist barrel. That damn thing rocks. ;D