With all this love of the glorious 6.5, many long range shooters are using 6mm. But when it comes to hunting large cervids, I’ll stick with .30s for insurance. 25-06, however unpopular, is a great cartridge. As is the 270. As for brass availability, if you can get it then I don’t concern myself wether it’s easy or not to get. After all, with the internet, how hard is it to get brass?