I've repeated this on 3 or 4 Encore barrels, so I know it's not a fluke. All the barrels, both SS and blue, were the medium sporter weights, not the heavy weight contours.
When you get the barrel, go through a careful break in process. This means anything along the lines of (1) about ten shots with full cleaning between the shots, followed by (2) about five 3-shot groups with full cleaning between the groups. All the above should be done with copper jacketed bullets (no moly).
Once this is done, then switch to your primo 223 ammo and do some accuracy testing. My pet 223 load, that works in any of my 223 rifles (SS, semi auto, or bolt action) uses a Berger 52 Moly bullet. Whatever load you choose, don't exceed 55 grain bullet weights because of the slower twist in the Encore 223 barrel.
In every case, after the proper break in procedure, I can shoot 100 yard 3-shot groups with the Encore barrels that have all three shots touching. And this can be repeated multiple times. That 223 Encore barrel is amazingly accurate. I'm talking sub 0.5 inch groups.
Good luck,
B. Noz.