You will have 3 set screws, 2 on the stock side and one on the butt pad side in between the other two. Find an Allen wrench that fits the one on the butt pad side and loosen it enough to slide the butt pad off. There will be what looks like a rod in the middle sticking out. In the center is a Allen screw, like Tron said turn it counter-clockwise for more tension. Reinstall the butt pad and you should be ready to go.
I have mine set so when I shoot the highest FPS shell (fastest) the unit will not quite bottom out as per factory instructions.
It is important for the Gracoil to be adjusted to the shooter, not the load or shell size. When adjusted to the individual, the recoil will activate the Gracoil and it will respond to protect the shooter.
Not all shooters mount or hold a gun with the same pressure to the shoulder and face. If the tension is set too light there will be more gun motion than necessary, and it could compress enough to pinch the shooter. When the tension is set too heavy, more recoil is felt. The tension should be set tight enough that the unit will not completely close, or “bottom out”.
Setting the Tension
Open the unit using a 3/32 allen wrench, insert it into the hole on the right side and loosen the set screw 2 turns, then pull the plate off exposing the center shaft. Using the same allen wrench, insert it in the hole in the shaft and turn as the arrow indicates, towards the lightest setting and replace the pad plate.
Mount the gun as if you are about to call for a target. If the unit starts to compress, it is set too light, so remove the pad plate again and turn the center shaft 1 turn towards “Heavy”, replace the pad plate and mount the gun. Repeat this process until the unit does not compress. Do not go past this point more than ¼ turn. It is now set on the “breakover edge”, any amount of recoil will activate the Gracoil, giving quick response with a short stroke, and absorbing a greater amount of recoil for a softer shot.
Pad Plate Adjustment
The Gracoil pad plate is guided and runs on 4 teflon liners for smooth motion and lifetime wear, a small amount of oil on the guide pins occasionally will help keep it running smoothly. To adjust the pad plate for the shooter’s comfort, remove the recoil pad using the 3/32 allen wrench, then use the 1/8 allen wrench to loosen the 2 screws holding the cam locks. Both screws have a series of 6 holes for adjustment, simply move the plate to suit your comfort and retighten.
Length of Pull Adjustments
If you have a GC15LP Gracoil with length of pull adjustment, use a 7/64 allen wrench to loosen the 2 screws on the right side of the stock plate, then turn the center shaft to your desired stock length and retighten.