.25 Cal Hatsan BullBoss - Hammer Spring Adjustment

Figuring out how to increase the velocity of my .25 Hatsan BullBoss. It was shooting JSB King Heavy 34gr pellets at about 780 FPS but I wanted to see if I could get it up to 840-860 FPS. Was sighting in a new scope too (Burris Droptine 4.5-14x42mm), but I need to unmount and shim the scope as it was shooting wicked low. Actually shot me a dime sized, 3-shot group from 74 yards away (I was aiming 6" above the point of impact). One of my best groups ever! To make the hammer spring adjustments, the gun needs to be uncocked. I used the #4 and #2.5 allen wrenches. The #4 is the wrench that adjusts the hammer spring at the rear of the gun. The #2.5 holds the hammer/bolt in place while making the adjustments. #4 wrench counter-clockwise = more power clockwise = less power