I'm just grasping at straws here. A local guy had a Remington Varmint rifle chambered in .223, however it was barely a .6" to .750" rifle, big scope, off the bags at 100 meters. I don't know what his loads were, but he was a handloader.
He was shooting it at the range the day I was shooting groups from my CZ 527 in .22 Hornet. 3 successive groups on one page of targets with the Hornet, ran .105", .165" & .308. They were comprised of 2 different loads, with 3 different bullets, a 45gr. SP and two 40gr. HP's.