Unless something is wrong with the gun to start with, I wouldnt think a tune on a PCP is going to have a marked impact on accuracy. I own more than a few PCP's and generally, they will be just as accurate as the shooter. With springers, it's a bit different as a tune will increase the effectiveness of the shooter through less recoil, smoother recoil, smoother operation, etc, etc... but with a PCP, there generally is no recoil to speak of.
With the smaller tube on the Raider, keep in mind that more power = fewer shots.
I'd say unless there is something wrong with the gun, just enjoy it within it's limits and if something is wrong with it, give Tim McMurray a ring and see what he can do with it.
