Oh boy, lot of myths, hearsay, and pure falsehoods in this thread.
Since when is a .338 RUM a wildcat? If that's the case the .300 RUM is also a wildcat, as its based off of the .404 Jeffries. Both ultra magnums are here to stay and will have many different ammunition manufactures involved with them for some time to come. The Remington Ultra Mag is just as accurate as any other round, actually its more accurate than 99% of them at long ranges in the right gun. I have seen the .300 and .338 RUM shoot sub 5" groups at 1,000 yards using hunting style bullets and a muzzle brake! In fact I watched a hand-loaded 200 grain Accubond shoot a .375" group at 400 yards in 10-12 mph crosswind from an out of the box Sendero. This was from a standard wooden table using a bi-pod and rear sandbag, even saw a 1,381 yard killshot on a deer with the same round from a card table! Granted this is not typical but is achievable in any properly built gun, do not tell me this round is inaccurate....
The Winchester Mag is a great round with a long military background, nothing bad to say about this round.
I have found the cost per round is a moot point, you will overheat the barrel and your shoulder before anything else. The barrel will typically last around 1,000-1,300 rounds before throat erosion becomes a serious issue. To get the accuracy achieved above you will need around 200-250 shots and a ton of patients. Even a light hearted approach can net some serious accuracy from this round though.
If you want any info on the RUM round just let me know.....
Strip