Wag is caused by too much gain, either in the radio or mechanical. Mechanical gain can be raised by moving out on the servo arm or reduced by moving in.

My 401 on my rex with a 9650 digital servo is 32 percent in HH mode with a hole that I had to drill as close as I could get to the spline of the servo.

With an hs50 make sure DS mode is off (if you have been running with it on just throw that servo in the trash and start over) and that you have some delay set on the 401.

Also make sure that your linkage is as silky smooth as you can make it and if its going through the fin brace, I enlarged that hole as well and squirted some triflow on the rod where it passes through there.