Can't seem to find anything big enough to do more than a dozen cases.
Recommendation? Without buying a cement mixer .

its not cheap($800+shipping) but thumler makes a 40lb tumbler..
if youre handy id look into building one..i wouldnt have bought my 15lb thumler if it wasnt only 180 shipped. most sites it goes for 240 or more. at that price id just buy a heavy duty motor and the necessary parts.

http://idpaforum.yuku.com/topic/8193/Homemade-wet-tumbler-for-stainless-steel-media#.Uq1HFfRDvXs

http://www.ar15.com/forums/t_6_42/344986_.html

this is the link i meant to post. much more detailed. if i wasnt so lazy and didnt find that cheap 15lb thumler i would have made attempted this.

How about that big Dillon tumbler?
addendum:

I just got home and eyeballed a 50 cal round and the case is about 3 or 4 times larger than a 30-06.
The big dillon holds 550  '06 shells so I would guess that it could do 100 easy.
It's a dry tumbler only though.

I was looking at the 15lb from thumbless. How  many 50 can you fit in that?
Have bearings and a motor , just need  to get motivated to weld.

I was looking at the 15lb from thumbless. How  many 50 can you fit in that?
Have bearings and a motor , just need  to get motivated to weld.

not many. i dont shoot .50 so i dont know the exact number. i do have a few bmg brass on hand and they are huge..15lb can easily fit 250 9mm and since .50 cases are about the size of six or seven 9mm brass cases i would guess between 25-35, 50 max

This doesn't answer the OP's original question but suggests an alternative.

My guess is that you won't be firing hundreds of rounds at a time like you can with an AR15 before reoloading. You'll probably have 100 rounds or fewer. If this is the case, you may avoid spending hundreds of dollars on a tumbler large enough for your cases if you just clean them individually by spinning the cases in a drill using a Lee Precision Universal 3 Jaw Chuck and #0000 steel wool. You can clean 50 cases in minutes and the cases come out super clean. I did this for a while with my large caliber rifle rounds before acquiring a tumbler.  If all I shot was large caliber rounds, I probably would have stuck to this method.

If one don't want to make.  This guy sells them.

http://biggdawgtumblers.net/

this past weekend ive been working on improving the efficiency of my rotary thumler.. i wasnt that satisfied with the recommended load of only 2 lbs of brass.
after doing some reading on reloading subforums and some trial runs i found i can fit quite a lot of brass and only need 3-4lbs of stainless media and about 2/3 gallon of water. i just put it about 1" above the level of brass.

they recommend 5 lbs of pins, 8 lbs of water(1 gallon), and 2 lbs of brass. as of right now i can run double the brass by using only 4lbs of pins, 5-6 lbs of water and the remainder is brass. ill do more experimenting and update later.