They have one major flaw. Not enough elevation adjustment on the rear sight! I had to rig up a long range vernier sight behind the receiver. With the stock Williams sight, my gun hit 4"-6" low at 100 yds, with any ammo.
They are pretty accurate, and with a trigger job, and correct rear sight, they can shoot.
Another solution to the rear sight, is a spacer and longer screws to remount the Williams. I'd guess it would need 1/8" or so to get to 100 yds, more for longer distance.