i looked at this before purchasing my 5r it has the same rifling just in a triangular barrel also 2 inches longer as far as i know. i havent had any experience with it but i steered clear. you can buy a normal 5r sell the factory stock and put that same B&C stock on it for alot less than 2g or put a better one on and still be under, the only other thing i think that is different is they put a larger bolt knob on from factory