I have a pair of Coopers in 221FB, I love them! It makes about the best little PD round out there. Its efficient only 14 grains of powder to get a 40gr bullet going 3400fps. Barrel life would be forever in a hunting type rifle and a long time as a PD rifle. Almost no recoil and its terminal performance on little critters is awesome. It will suck'em right out of the hole on closer shots (100 yards or so) for longer ranges, I will shoot it out to 275 or so, much farther and its nice to have something with a bit more get up an go. I have wacked a few 300 yarders with it though.
I made up my mind last night, I am getting just one more this next year. Its going to be a Dakota Predator in a 17FB