Ammo is available, but it's spendy at better than a buck a round. Loading your own is a pretty viable option. RCBS makes dies and there are at least a couple of companies that make brass. Hornady makes a .300 28 grain bullet. I suspect that none of it, though, will be in stock at your local dealer.
I guess that it all depends upon how much you want to shoot that caliber. It's an interesting rifle, to be sure.
Well we don't rent pigs and I figure it's better to say it right out front because a man that does like to rent pigs is... he's hard to stop - Gus McCrae