I'm trying to work up handle loads for my ar 15 .223 18" wylder mid length gas system 1-7 twist. Been trying 77gr smk using varget & IMR 4895 best group I can get is 3/4 inch at 100 yards like to get 1/2 inch am I asking to much for this setup or is that about right for 18" barrel. I got some other bullets and powder to try. What's your thoughts?