My view on long range shooting, in my limited understanding (keeping in mind I have very little experience in the area), is that:
--If you're killing just paper, there is no need whatsoever for a .300, .338, or larger caliber. A 6mm or 6.5mm round is what you want, even for 1K range shooting, maybe a 7mm round tops, because it will do just as good of a job at bucking the wind (through good BCs) with a whole lot less recoil, noise, expense, etc.
--IF, on the other hand, you want to theorize that you may have some practical anti-personnel or anti-material application someday (in the event of invading Al Queada forces or whathaveyou), and want enough retained energy to actually have enough thump to kill a car at 600 yards or a man at 1000, let's say, then I could see going to a .338 Lapua, .338 RUM, or even .50 BMG.**
But the 6.5 mm rounds like the 6.5-284 Win/Norma actually best the .300 win mag, for example, in drop and wind-bucking at 1K, because high BC 6.5mm 139s go a lot faster than high-BC .308 190s or 210s. So why go to a heavy recoil-producing, flinch-inducing monstrosity when a 6.5mm cartridge does the job even better than a .300 maggie and about equal to a .338 lapua (for killing paper)?
Heck, the 600 yard world's record (sub - 1" group in fact) was set earlier this year by a
6.0mm round. But at 1K, I think you'd want a 6.5 cartridge or possibly a 7mm cartridge.***
If you want to go budget/non-custom, this would be a tough act to beat right here:
http://www.gunblast.com/Savage-12F.htm
**Having said that, I think that a 6.5mm round from a .260 rem, 6.5x55, 6.5-284, etc., would still pretty easily kill a man at 1K yards, because it still has 700-900 ft-lbs. of retained energy, if you're talking screaming high BC 139s. I for one would not stand there letting someone take shots at me at 1K on a bet that if I survive a hit, I would win $1 million.
***The great thing about the 6.5 cartridges such as the .260 rem, 6.5 creedmore, 6.5x47mm, and 6.5-284 Norma, is that since so many long-range practical and F class guys use these calibers, what happens is that very high quality brass and bullets end up being made to supply them (Norma, Lapua, etc.). You need these high quality, consistent components to maximize your chance for extreme accuracy. So that weighs in favor of going with one of these 6.5 rounds. And of those, the 6.5-284 has the most oomph *among those cartridges not considered to be barrel burners*. I've never done an F class match, but my understanding is that a lot of them are now turning to the 6.5-.284 Norma.
On the Horus reticle, I am not educated enough to make a recommendation one way or another. But it sure does look good!
That's caliber - as for equipment, that's a whole nuther topic. I don't have access to a 1K yard range, and my "little" .243 win poor-man's custom build is enough gun for the 600 yard range I do have access to. Having said that, I still do indeed plan on getting the Savage 12 F Class PTR in 6.5-284 Norma within a year. Better wind-bucking is better wind-bucking, even at a "measly" 600 yards.