[Tim Hancock]

Len, most manufacturers of AR15 (semiauto version of the military type M16) ccomponents build them as 5.56 Nato which allows the use of surplus 5.56 or .223 civilian ammo. Some also manufacture .223 wylde chambered barrels which will not chamber the 5.56. the .223 only barrels are typically only used by some match shooters. Most AR15's are the standard 5.56/.223 chambers.

Go to AR15.com for tons of info on these things. There are several companies that offer kits for putting one of these together. I went with RockRiverArms components which are top notch. I ended up spending about $600.00 for the components which took me one evening to assemble. You will will find all kinds of different variations in barrel length, sights, grips, stocks etc etc.

Good brands of complete new rifles are Colt, Bushmaster, Armalite, RockRiver Arms (cost for a completed firearm will vary from $800-$2000) There are many component manufacturers also and most will mix and match (building a no frills "kit" or component gun will cost $500-$700).

I am not a gun nut, but be careful, reading the AR15.com forums sucked me in big time! Now I am looking at flashlights, lasers and holographic sights all while trying to convince my wife that I "needed" this gun for varmints (in reality, my multiple 22's and shotguns are more than adequate for dropping the occasional possum, coon, skunk or woodchuck that comes up to our deck at night to steal our catfood!)!