Im gonna have to second what mostly everyone else said. The key to being a competent LR shooter is practice. With that said, the .308 or .260 are perfect. Theyll handle mostly everything excluding Elk and bigger, though some would disagree. For just beginning the long range journey though, nothing is better than a .308 IMO. It lays down the ground skills that you need most and once you get good with it, ie wind reading, etc you can get rebarreled to .260 and have a ballistically much better round along with the skills to take advantage of it. Not to mention, .308 has like a 10,000+ round barrel life depending how you treat it, which equals lots of practice time. Plus, besides maybe .223 I would have to say .308 is the cheapest and easiest round to reload for.
With that in mind, I would get a Remington 700 short action, good quality 20"-26" barrel(you name it, Bartlein, Krieger, Lilja, Brux, Broughton, etc theyre all good), and a Mcmillan A3-5 or A-5 stock(personal choice) and take it to a smith, hopefully with skills on par with somebody like Mr Shawn Carlock or Mr Kirby Allen(though I know Mr Kirby doesnt mess with the factory actions much) and have them true/blueprint the action, glass bed it, and work the trigger down to your weight preference(I like it right around 2 lbs.). I havent shot the new X-mark trigger but I have shot a Savage w/ accutrigger and personally did not like it, but thats just me. Free floated barrel goes without saying here obviously. For optics, it cannot be stressed enough that if youre gonna skimp anywhere, dont do it here. As was said, Vortex has very good quality stuff for the money, probably the best quality per cost out there. Other than them, Leupold and especially Nightforce makes very good stuff. If I was rich, Id get a March, but Im not rich. Also, US Optics and Schmidt and Bender are bad to the bone too if you got the money.
As I said, the Mcmillan stock is a personal choice, run what you want, a factory stock is perfectly fine, but IMO there is nothing better for prone shooting than the A5. Ill admit though I havent shot an Eliseo or any of the other tubeguns and I hear a lot of High-Power and Prone competitors singing their praises(think of stock with basically adjustable everything). You may want to check out Mr Carlock`s website Defensive Edge or GA Precision as they very well may have what you want, and if not they could build it for you.
Thats probably more than you wanna spend though, and if so, just like I said, get a known recommended smith to put together a Rem 700 and quality barrel and glass bed/free float barrel/trigger work as you see fit and you should be able to have a rifle done that should be capable of 1/2 minute groups with the right load if you do your part. Also, with the .308 and .260 and other cartridges with a similar expansion ratio, theres really no need to go above 26" as you wont be gaining much velocity and the longer the barrel you get, the less stiff its gonna be, translating to more barrel whip and consequently less accuracy. Hell, with a .308 I wouldnt go above 24", as I said what you gain in velocity POTENTIALLY could be lost in accuracy, though it would be negligible at 24 vs 26". Either way, shorter barrel means less weight with the same contour, or a heavier/stiffer contour at the same weight.
If you dont even wanna do that, then something like a Remington 700P or Model 700 SPS Tactical or SPS Varmint could meet your needs.
Hope that wasnt too long of a post and that maybe just a little bit helped. LOL dont take my word as gospel but it should atleast set you in a general right direction.
Blake.
