To the OP: The 204R will do what your friend wants, period. Of course there's other calibers that will do it also, but you asked if the 204R would do it, and the answer is "yes". She's a real beauty
I shoot everything from the 17 CF's to the 6mm's, and for just rat popping, the 204 will do it well. Hell, I shoot rock chucks with my 20VT out to 300 yards, and it could be considered a "204 Short", so the 204 with a bit more horsepower does it just a mite better.
Rock chucks with a 20VT? Sure....
You can get more muzzle blast, more recoil, and NOT see your shots/hits with other more potent calibers if wanted, but for the pure pleasure of seeing all your hits with laser-flat trajectory with almost no recoil, well then, the 204R would be perfect for your chuck shooting friend. JME