I believe Craig Bodington did a write up on that caliber? Either an STW or RUM cartiridge necked down to a 25. You'll get 4000 fps and shoots out to 500 with very little drop. Obviously for such performance you'll be giving up something...barrel life. Should be fun to shoot and a good gun for you varminters out in the midwest. The only problem is if you can only run 1000 rounds through it. I'd be screwed after a few weeks, b/c I'd be pumping a lot of rounds through that one.
It would be nice not to worry about ranging and dialing a scope in, though. Just put the crosshairs on it and pull the trigger. Throw in another $500-$600 and have him make you up another barrel, ready to put on for next year