How much have you used your pistol? Round count? Shadow 2 Orange is pretty tight fit, and might get smoother with a bit of use. My Custom CTS variant (TS slide, SP01 Shadow frame) was so tight, It wouldn't return to battery with any spring under 16 lbs initially, and was still slightly sluggish. After about 2k rounds, it functions pretty well with 13 lb spring using factory ammo.
Ammunition and pistol fit would both have an effect on the type of recoil spring you could settle with. Too heavy a hammer spring can also complicate matters, but thats another chapter. You could use a lighter hammer sping, but check for light primer strikes on all the different primers you use. Hammer spring influences the motion of slide during the recoil cycle.
