No 1st hand experiance with 7-30 but I always thought the idea behind it was to be primarily used in Contender type hunting handguns. Personally I don't get the 7-30 Waters concept either. Provides a bit more range and less recoil than a 30-30 and I would think much less recoil than a Contender chambered in 7mm-08.

I would think that your friend should be able to neck down 30-30 brass but the reloading experts on here would probably be the people to ask.