To balance out my gun and defeat recoil, i installed a mercury tube but put it in the mag tube instead of the stock, this keeps the weight of the gun more forward and keeps the muzzle down when shooting... it is by far the best performance that I have found!!! I put the 4.5 inch reducer in the mag tube but just so happened to have a shorter spring laying around ( about 13 inches) , take out the plug and let the reducer act as the plug... I can still hold two 3.5 inch shells in the mag tube. Good luck!! jrs