Given that it withstands the recoil on a 12ga 870, I'd say yes it will work fine on a 20ga 500. :^)
BTW, the 1-4x with a circle reticle is nice for feral hogs. Dial down to the 1x end in heavy brush for super fast accuracy, dial up to 3x when working the edges of fields to center that 75yd shot.
Let us know how it works for you!