Best I ever done at Camp Perry was back in 2011, before my eyesight started going.  123gr .310 diameter Hornady V-Max @ around 2500fps.  The barrel on my rifle was like new and I could stick them out into the rifling near max length.  With the high nitro powder I was using, it wasn't long and that was no longer happening!  Few spitzer bullets will get you out there and remain within magazine length.  I'm going to give Nosler 220s a try someday, though they are expensive.  BC is as high as a 173gr FMJBT!  You're working in the right areas, it's just a matter of getting the rifle's opinion!