I am also seeing a lot of 54R, which is great, I've been slowly stockpiling it up. I am seeing factory ammo from the Russians, and it's great to know that the gun will run anything through it. My brother and I were discussing K98s the other day and I had to forewarn him that there is just absolutely no way he'll be able to feed it (living in Chicago, I can't get any ammo shipped here... ugh). I went with an Ishapore Enfield recently in 7.62 NATO expressly because I knew I'd never find .303 at any of my local shops.
That samco link that someone posted should help. I've dealt with them before on a rifle and they were solid. Just... hard to understand over the phone!