A 1 in 14 inch twist is slower than a 1 in 7 inch twist.
5.56 is not the same as .223. The specs for the 5.56 are military and the specs for .223 are SAAMI specs.
You can safely shoot .223 in a 5.56 chamber, but cannot safely shoot 5.56 safely in a .223 chamber.
RE: twist: got it reversed...sorry....i do the same thing when i argue with my girlfriend whether black is the absence or the combination of colors.
Re: .223 vs 5.56. I have never EVER had, seen, or known of a FTE, FTF with any AR with either ammo on our range. The only time I have seen an FTF or FTE is when we screw on a suppressor to our full autos.