I am assuming the SP series is close to the GP100 and if so you can do it yourself.
Midway USA sells Wolf springs and these alone can lighten up the pull. When I did my GP100 I took a few hours and a bottle of Flitz polish and polished up all of the trigger parts until they were glass like smooth.
Midway USA sells Wolf springs and these alone can lighten up the pull. When I did my GP100 I took a few hours and a bottle of Flitz polish and polished up all of the trigger parts until they were glass like smooth.
