Its a 'cat but I don't know of anyone that has one. The 7RUM is way overbore as it is, and going any smaller makes the problem worse. I'd be intersted to see what kind of throat life the 7RUM has, is it 1000, 1500, etc?
there is... its called the 270 allen mag. from what i have read, it is a 7RUM necked down to .277.
dont know much about it but have seen talk about it on longrangehunting.com
Casey
It would work really well with a 28-30" barrel, but anything shorter would really hamper its potential. I can imagine that a 130 gr bullet at 3800+ fps would shoot pretty flat.