MIchael a reflex sight is the only way to go, but going to the rail adaptor you chose sets the sight height too high above the barrel. This sets up the requirement to hold over the target at close range. I tried several different reflex sights and mounts and I now use a reflex sight that has a 2mm dot and 12 different intensity settings. I found this best for all light conditions. I also use an adaptor that converts the 11mm rail to a 22 mm rail without raising the sight height. They use two wedges and are very inexpensive. I now shoot my GK1's more than any other airgun and I am considering another one in 177 for low power pesting. You will be incredibly impressed with their accuracy and trigger. I feel they are every bit as accurate as a 10 meter Olympic pistol with a lot more power.