For precision out to 650 & farther I would recommend 6.5 creedmore, 6.5x47 or even 243 at least 22" barrel, 20 can do it but u lose a little fps
Don't worry about running hot, what alot of guys are looking for is an accurate load learn your drops. The problem guys have had running hot is a little moisture on the ammo make them very hard to extract the spent casing. This is just range talk, I do not have experience shooting in the rain.
What is important is have a rifle/ caliber that allows you to see your impacts. Gravity doesn't change but the wind sure does.
Long range Rifle two years ago was a great deal of belly shooting, precision rifle is looking more like 3 gun with structures , paper 75-100 yds one inch targets with time as a stress factor, barrels, roof tops and vtac walls are common place with shots 400-1000 yds @ 1-2 min targets.
Most shots are under 750 IMO
2 years ago few MIL guys in Oklahoma now majority of precision guys have first focal plane mil dot scopes
hope this helps
later
Corey