Mudrunner,
Are you talking finding it locally because I have had the same issue but online its never been an issue. At least not when I have needed it. It was my grandfather fav for yotes and the small TX deer found around I-10 corridor west of Houston. It rubbed off on me big time so......
For example of its availability online, right now: grafs , midway, cabela's. Between then there is Hornady, Prvi Partizan, Wincheser funny how they did not have rem brand for a remmy round LOL. That was just the first big shops I checked and all had it one or more brands.
Then if you are either in a real jam and can not find any or want rock solid high pressure cases you can pick up 7x57 RWS and form it to 6 Rem. A bit of a PITA but they were doing it for the 6 Crusader a blown out shoulder body 6 Rem wildcat.
When I get a rifle setup I usually always buy enough brass for a few barrels worth. If its a hunting rig that is a life time.
Now I will say if the remmy is a no go and since it seems you have no issue with COAL I think the SLR would be my choice over the crapmoor LOL ( just kidding its a GREAT round I just am naturally averse to anything that mainstream with that kind of koolaide following even if it really truly is a great round) The SLR needs nothing more than a single cycle thru the fl die. You get a much nicer neck which can be put to use in a nice long COAL receiver.
I have really always been a fan of long case neck, long sleek high BC with their stretched COALs when seated ideally. Its why I end up with wildcats so often I guess LOL. Its one of the things I really liked about the sako trg-22 when I bought it. Detach mag with just shy of 3" COAL clearance. We won't mention the mag costs though !?@#@?
But really, if you are building Remmy now, go pick up 300-500 cases as you can get them currently and you are all set for a few life times or more of hunting. Minimal size, anneal frequently, keep pressure within reason, and they will last and last.