30-300 win is good--and heck it does work--just about like the 33 Nosler...but I gave up on wildcats long ago. I like to be able to order brass, dies, and maybe even walk out with a box of ammo if needed...
I built a 33 Nosler at the end of last year. I'm left handed and built mine on a Montana 1999 long action. I put a magnum mag box and a 26 in proof barrel. When I did order a reamer Dave Manson did a tapered throat on it for the Berger bullet (250 elite hunter). I have tried 3 bullets in it:
1. Barnes LRX 265grain-- seated out as far as 3.55 I could not get sufficient speed for me to be happy. They were all lumbering around 2600 fps.
2. Cutting Edge 225 grain. Seated to 3.53. I got 2994fps adv. and very accurate. This is a great bullet for the 33 Nosler. (Not a hot load could get more velocity in my rifle)
3. Berger elite hunter 250 grain. Seated to 3.54 adv speed of 2720fps. With very good acccurcy...(not a hot node either, but shoot really well so I left it alone)
I do want to say, I'm happy with it, but if you want to shoot heavy 338s...I'd stick with a 338 ultra, Edge, Norma, or Lapua. 250s are on the heavy side 225 are probably optimal and really 280-300s are a no go due to MV around the 2400-2500fps mark for my rifle.