In a long range rifle the need for a semi-auto is mostly mitigated. Now with a harder recoiling cartridge like a .300 Win Mag or a .338 Laupua the advantage of the semi-auto action is is reduces recoil (at the expense of weight).
But you won't shoot it any faster and I can keep pace on any timed course at 600 and beyond with any semi-auto with a bolt gun. The thing that takes time at that distance isn't cycling the action its recovering from recoil and settling back down into position for a carefully aimed shot. From a theoretical standpoint the semi-auto should still have the advantage. From a practical standpoint the mechanics and efficiency of th machine still default to the biggest bottleneck in the whole equation and that's the trigger jerker. In 30 years of Highpower and other rifle competition with several state and regional championships and having shot right next to world record holding names I've NEVER seen anyone come close to shooting to the mechanical potential of their gun. Not once...
Me personally, I'd opt for a bolt gun in .338 unless I was shooting in competition that restricted my ammo choice. Cost isn't an issue if you roll your own (which I do). But I seriously don't need and won't shoot such a rifle. Too many other shooting interests and if truth be told shooting targets anything past 300 yards is a pain in the ass unless you have a well schooled spotter, a spotting scope that costs as much as the gun, or access to a range with pull targets. Shooting such a rig at 100-200 yards is pointless.
While an AR in either of those calibers is interesting. I shudder to think of the weight involved.
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