Thinking of trading in several "hunting" weapons
on something "tactical".

Not exactly. As I remember it is okay to shoot the 223 in the nato chamber but not the nato cartridge in some 223 guns as it is loaded to a higher pressure.

S4s4u
You are right and some of it won't chamber. Found out first hand.

Cranberry Township, PA?! I was in that area yesterday.

I myself not being into the tactical stuff much did some checking a while back and the difference is the twist rate of the barrels as the nato is designed for heavier bullets and chambering problems are generally from too little free bore for the heavier bullets. This is what I was told but when I looked up the two loads in the same book which I believe was Hornady the bullet weights were different for the two. I've talked to guys that shoot both with no problems out of the NATO and others with 223's that wouldn't chamber the NATO ammo but if you look at the case dimensions they are exactly the same case so the bullet just about has to be the only difference. I'm not completely sure that they all use different twist rates either but that's what I was told. My only experience with tactical stuff are my auto pistols and my AK's which would shoot rocks if you glued a primer and some powder to the back of it.

I forgot the part about the trade, if you want a precision shooting weapon go with the 5.56 AR but if you strictly want a defensive weapon buy an AK. They are a fraction of the price and ammo is cheaper not to mention they are extremely reliable. You can trick them out just about exactly like an AR by adding rails. If you think you want to go that way let me know and I can tell you some of the things to look for. I had actually figured if the handgun business didn't take off I was going to re tool and start building AK's out of parts kits and selling them.