Many years ago my good friend and Varmint Hunting partner "Irv" acquired one of the first "heavy barrel" AR type Rifles.
He strapped a Leupold 6.5x20 variable power scope on to it and went to town!
He used Winchester 223 brass and loaded his ammo for this Rifle on a Dillon progressive press - and then you could have knocked me over with a feather when he began shooting (consistently!) 3/4" five shot groups at 200 yards with this set-up!
I have seen him do this a dozen times there at the SPAA Range in Tukwila, Washington.
I have seen Irv take Rock Chucks with this set-up in excess of 1/4 mile away!
And probably some Prairie Dogs as well but my memory is not clear on that point right now.
I like Winchester brass in my 223 bolt guns but I also use LaPua, Federal, Remington and Hornady in my many and varied 223 bolt guns.
Best of luck to you in your decision making and brass availability.
Hold into the wind
VarmintGuy
