I'm not sure what your barrel length and twist are, but if I were going to shoot the 230 OTM I would want atleast a 26" 10 twist, even better with a 28-30" to break 2800fps a lot easier, but since there isn't a huge difference between the 215 and 230 OTM bc wise, i'd stick with the 215 as the heaviest in a win mag.
+1 on the 215, IMO it may be one of the best hunting bullets out there for rifles in the various 300 magnum chamberings. I also aggree whole heartedly that if you don't have a well ironed out system of reloading your throwing good money after bad results using the Bergers, and to a lesser extent no matter what bullet you load. There is a lot of good advice in this thread. I wish I would have had a computer 10 years ago when i started loading my own ammo, it would have made life a lot easier. I didn't start out loading high dollar bullets. I like nearly everyone else started out with the Nosler partitions and BT, the Hornady IB and SST and gradually over time realized I had reached the point that I couldn't improve the accuracy anymore no matter how many times I sorted the bullets or how much time I spent preparing brass. I could only get to 3/4 MOA consistently, from time to time I could shoot a real nice 3 or 4 shot group but invariably there would be a flyer that just didn't figure with the level of preparation I was loading at. I tried the Berger 230g tactical OTM purely out of frustration as I knew something was amiss. I stumbled on my load with the third group I shot. Lucky? Sure. What holds my attention is that as long as I do my part it will print 1/2 MOA 5 shot groups until I get the flinches. IMO I wasted a lot of barrel life (300+ rounds) messing with stuff that just wouldn't run I wish I would have moved to a "expensive" bullet a lot sooner, it would have saved me a ton of barrel, time and money in the long run. YMMV