The .30-06 Springfield cartridge (pronounced “thirty-aught-six” or "thirty-oh-six") or 7.62 x 63 mm in metric notation, was introduced to the United States Army in 1906 (hence “06”) and standardized, used until the 1960s and early 1970s.
I have only owned a pistol, never a rifle and now I am browsing for an AR. I have spoken with several folks about proper ammo and some say use .223 or 5.56 as they are the exact same. Do all AR-15 rifles accept either one unconditionally?
If I purchase one called a flat top, is it still possible to mount a carry handle on it without having to buy a new upper? Also I like the old look of the Vietnam handguard that was a little more triangular than today's round and picatinny style. Is there a website that might sell something like that, or would I have to look at an entirely new upper reciever?
Great, I thank you all for your help.