It is very easy to form 350 brass from other belted magazines. I've done it with 7mm RM, 338 WM, and 300 WM.
If he is interested, I'd sell some loaded ammo...
I have a few boxes of 200 grain factory loads. I see that the cheapest on Gunbroker is $75 per box. I'd let these go for $50/box plus shipping. I also have a couple boxes of 250 grain Factory Loads - these are difficult to find -- $90 per box??