After much research and considering a number of manufacturers and custom building, I've settled on a DPMS Recon. Although discussion about my selection can take us deep into the woods, I'd like to avoid that for the time being. But, being new to the world of AR-15s, I have some questions (some may be silly, stupid and may fall into the category of "if you don't know, why are you getting and AR-15?"). Be that as it may, here goes: 1. Will any standard AR-15 magazine work with the DPMS AR? 2. If other mags will work, what are the "good" ones and what are the "bad" ones 3. Are the mags for .223 and 5.56 different or the same? 4. Is the DPMS capable of the same mods as a standard AR-15? That's a good place to start, anyway. Thanks!