I have a number of long range rifles. A couple people have mentioned the 30-378, but I have not had good luck with mine. It has a short action and a short clip plus a long throat, which means that unless you do some tricky reloading, the bullet has to go on vacation to get to the lands. You have to seat heavy bullets so deeply into the case that they can actually bend from the force of the burning powder before they can get stabilized in the lands. I recently read an article on this very topic. I have a Remington 300 RUM that I would recommend highly. You get that wonderful Remington action, long enough to load any depth you please, plus you get the best off-the-shelf barrel on the market. I also have three Remington 300 Win mags that all perform superbly. My Sendero, after 16 years of use, will still put three bullets in the same hole at 200 yds. I have a Sako in the Lazzeroni
Warbird, and I love the cartridge, hate the rifle for the same reasons I do not like the Weatherby. I have a Lazzeroni in the Warbird, but I have not shot it yet, so I cannot comment on its accuracy, but the rifle is superb. I have a Remington titanium in 30 Gibbs, which holds my record for killing a deer at long distance, 837 yds, but I have to admit that had to be a freaky accident. My bottom line until I shoot the Lazzeroni, you cannot go wrong with the 300 win mag. Extremely versatile, inherently accurate, easy on cases. It is just a great cartridge.