500 yards is a long way, but I can't see that any factory sporter weight offering is going to be whole bunch better than anything else, provided you practice with it and load for it properly.
There really is no "best" and I'd grab a new SC M70,a Rem 700,or most anything.Work up a good load and mount a good scope,practice.An extreme Weather in 300 WSM or 7mm WSM would be excellent....I have had the 300 WSM and know this first hand.
A 270 or 30/06,anything in that range will work just fine with a 6X Leupold and LR reticle.
I picked up a Ruger Hawkeye 7 Rem Mag about 5 years ago,mounted a 2-7 Leupold on it...it threw strikes from the get go at 500 with no tuning and 150 gr Federal Fusions.
