I purchased a 21" factory tapered 223 barrel for my Contender carbine and I am completely amazed at how accurate it is.
With H322 powder, Win LR primers, once fired Rem brass, 40gr V-Max I get 3400fps and have put 3 shots into 1 1/4" @ 300 yards.
Here is a pic of a coyote I shot last year with this set up the shot was only 40 yards I called the coyote in from over 400 yards away using a Primus Ki-Yi call and it was -30 degree celcius.