Re: Designing my Long Range Rifle
I own both, sort of. I have a Sendero in 7mm Rem Mag, and a Savage 110FP in 25-06. Both are the most accurate rifles I own. Nothing else that I own matches them.
The Sendero is heavier with a much nicer stock, nicer action and nicer (modified) trigger. It's quite the load if you wish to carry it anywhere - but you probably know that. This one will shoot 600-800 yards easily, factory stock, with factory ammo. At least, it should since it will shoot 1 inch groups at 200 yards. Next summer I'll find out how it does at 300-500.
The Savage has a bull barrel and a crappy plastic stock - though the stock doesn't compromise any accuracy. I plan to swap to a B&C Duramaxx stock this winter because it's the only stock that fits the rifle without going to a $400-500 semi-custom. Factory stock with factory ammo it shoots less than 1 inch at 200 yards.
If you don't plan on carrying the rifle much, I'd lean toward a Savage with a non-bull barrel and use that as your starting point. Carrying around either one of these is not that fun with the heavy barrel weight. If I were going to buy one to use specifically for long range and didn't want to mess with it I'd buy the Sendero. FYI, you'll still want to have the trigger tuned or replaced.
Graybull Precision builds long range rifles in 243, 264 Mag and 7mm Mag. I've seen their videos of a 243 and 265 shooting elk at long ranges, so it is possible. It all comes down to shot placement and your familiarity with the rifle.
For scopes, I'd look at a Sightron S-II or S-III, or a Zeiss Conquest. I own both as well as Leupolds, and I'd buy a Sightron or Zeiss before another Leupold again.