For me and in the context of extreme range hunting/varminting/rock busting (distances beyond 1500yds), the 338 cal is pretty much king..for now. The 300grMK is the most readily available bullet with the BC high enough to get the job done way the hell out there (effectively used beyond 2500yds). Wildcat is making some very nice exotics so this can change.
The goal is to maintain a velocity above the transonic range as long as possible. There is a concern that accuracy can go south badly when a bullet enters the transonic velocity and/or goes subsonic
So, the higher the muzzle velocity the better. Also, the higher the muzzle velocity, the less time of flight and less influence by the wind - all good things. In general, 2900fps is a bare min, 3000fps and faster is much better. Going over 3400fps does silly things to the 300gr MK so that becomes a mechanical maximum.
Think about it - 300gr bullet going 3300fps :shock: :shock:
You accomplish this two ways - big case or long barrel. Best of course is big case and long barrel (30" or longer). Yes, some monster cannons run barrels of 40" and longer. Talk to Lilja if this is of interest.
Until the RUM, there was the WBY (340 and 378) and the Lapua case. I left out the small proprietory cases as you still need to be able to get the stuff readily. Don't know of any Lazz suppliers in Canada and the Cdn Imperial didn't get going (Thanks Big green

). Plus costs go straight up.
The Lapua will not launch 300grMK at 3000fps from even long barrels. I don't believe in Kaboom type pressures. The 340Wby is way too small. Some used the 338-378 to excellent effect but the belt and case bulging becomes a pain.
A bit of digging brought out the 338-416Rigby improved. This case is equal or bigger then the Wby without a belt, excellent brass, and accurate. An instant success. With a 36" barrels, reaching 3300fps is not out of the question. That is serious horsepower. Just drop those numbers into a ballistic program then look at impact velocity and energy at 1500yds on out.
I was surprised to find out that this case was tested by the US Army in the 80's as a LR sniper/material destruction rd. Pity they didn't adopt it. Could you imagine the surplus brass...
So, here comes the RUM. Readily available, dirt cheap brass by comparison, and waiting to be wildcatted. Took about 2 min for new reamers to be designed.
The 338RUM case is smaller then the Lapua so already fighting an uphill battle. The next logical choice, the 300RUM case. This has been expanded to the 338-300RUM or 338 Edge. This case volume with a long throat exceeds the Lapua by a tangible amount and is pretty much the same as the Yogi (Lapua improved).
From there, we improve and modify the RUM case and voila, the Tomahawk and my idea of a better mousetrap, the 338 Mystic. Both will increase case capacity over the Edge by 3 to 8gr of slow ball powder. That increases the potential muzzle velocity by 50 to 100fps. Not a big deal but when faster is better, the small changes make sense, especially if running loooooong barrels.
These two wildcats get you pretty close to the 338-378 and wildcats, and the 338-416R without spending $2.50 per case.
The 30 cal is wonderful and a big case like the Wby/300AI, RUM, and 378Wby can do some wonderful things. For distances inside 1200yds, the Wby and RUM launching 200 to 220gr bullets makes a fantastic thumper. The 378 and long barrel RUMs just do the same thing further. These have been used effectively at a mile.
So, if 600yds is a long ways for you, then the Lapua, even the 338 Win mag is plenty. But if your goal is extreme range plinking, bigger is better.
Saying all this, I am playing with a couple of 7RMs and 162gr Amax. Amazing ballistics. No issue getting these to 2000yds, I think. Will have to find out after hunting season. Now that is cheap extreme plinking...
Jerry
PS Unless they have changed, aren't the Dakotas just shorter RUM's? If so case capacity is still "small". Funny, in this game 85gr of powder is small :wink: