Set the gun all the way back in the track and remove the rear stock screw. Turn the sled adjustment all the way IN just until you feel it bottom out. From there turn it back OUT about 1/4-1/2 turn. You'll have to play with that setting a bit to find what your gun and pellet combo really likes though. Once you find the setting you like, remove the adjustment and add some blue loctite and re-set it where you like it. I'm sure
@Motorhead can give you a much better idea of how to do it than I can though.
Edit: It actually may take as little as 1/8 of a turn. I dont quite remember I just know it really wasn't much of an adjustment outward from full in.