I have a 504, and mine is VERY accurate. Of course, mine is also chambered for .17 Mach II rather than .22LR, so that may have something to do with it. It shot pretty well out of the box, but after I pillar bedded the action around the round action lug, it became spooky accurate!
If you can find a Kahles 2-7X36 rimfire somewhere, I would encourage you to get it as soon as possible. It's without a doubt the finest rimfire scope I've ever seen. If you can't find one, another very high quality scope that would make an excellent rimfire optic is the Zeiss Conquest 2.5-8X32. Although it too has (sadly) been discontinued, they are still out there available for sale. It will work well as-is, but if you desire, Zeiss can modify parallax from 100 yds to 50 yds, making it more suitable for rimfire use.