[ QUOTE ]
I don't want to pay $30 for 20 pieces of 300 Dakota brass. I tend to lose brass if I fire multiple shots and that could get pricy in a hurry.
[/ QUOTE ]
I can understand your concern on the cost here. However you might think it over, when you step up to this level of cartridge, your not going to be blazing away at something. If your shooting the best made bullets, when they hit whatever you put them on, it is definately going to stop most if not all forward progress. Besides your more likely to loose the cases due to load development over dropping them in the grass anyway. Not trying to persuade you one way or the other, but if your ordering it from basically scratch, might as well get all you can from it.
Also going with the faster twist barrel, you can still shoot the weights you noted, but would also have the option of stepping up to the heavier weights for the longer ranges or bigger game in the future and you would have pleanty of horsepower to push them along.
I however, made a similar choice as you going with the .270 AM over the 7mm AM. I read everything that was posted on them both for a year before I finially made the decision to go with the 270. The overall decision maker was also economy. I simply had more bullets in 277 that I would never shoot in my standard Win. plus the 7 mm RUM cases were easily attainable as well as in my price range.
Either way, I am sure you won't be disappointed in the final product. Good luck and happy shooting.