In getting ready for a prairie dog shoot last week I bought some HSM brand 223 50gr ammo. This stuff out shoots anything I have used in my 14" SS TC barrel. At 200 yards I got 0.80" 5 shot groups. I have shot all the major brands of varmint ammo (Black Hills, Hornady, Nosler, Remington, and several others that don't come to mind). They work equally well in a friends Remington 700. I have reloaded for over 30 years and feel I know a few tricks for loading accurate ammo, but this stuff really performs!
I have just ordered another thousand rounds and will let my Dillon 550b rest for a while.
Edit to note I purchased mine from Cabelas.