Description Recoil springs are available in a variety of load ratings to allow adjustment of the recoil function to meet various requirements. All load-rated recoil springs include an extra power firing pin spring. For Use in: 39, 439, 539 ,639, 3904, 3906, 3944, 3946, 9mm 59, 459, 559, 659, 5903, 5904, 5906, 9mm 5923, 5924, 5926, 5943, 5944, 5946, 9mm 659, 909, 910, 915, 9mm Reduced Power…: 8, 10 & 12 Lb. Factory Standard.: 14 Lb. Extra Power……..: 16, 17, 18, 20 & 22 Lb.
