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  • Product Details
    Available in 17lb or 19lb. All ISMI Springs are made from silicone chrome instead of 150 year old music wire.

    Every ISMI spring is heat treated, shot peened & stress relieved to enhance durability, consistency and reliability.

    ISMI is a contractor of the U.S. government and produces springs used in machine guns with incredibly high cycling rates. Also, the creator of ISMI springs obtained his knowledge from extensive research in the development of springs used in Indy car racing.


    Warning: This product may be alloyed with trace amounts of lead and other elements which are known to the State of California to cause reproductive harm and cancer. To prevent exposure, do not alter the product by welding, grinding, etc. For more information, go to www.P65Warnings.ca.gov.
  • Reviews 2
    Customer Reviews
    1. THE LAST ONE YOU WILL EVER HAVE TO PURCHASE !!!!
      IF YOU SHOOT FACTORY AMMO / STOUT HANDLOADS, THIS IS THE H/S TO CHOOSE, ESPECIALLY IF YOU ARE ALSO USING X-POWER RECOIL SPRINGS. SO LONG AS YOU PERIODICALLY REMOVE FROM THE M/S HOUSING, CLEAN, & LUBE BEFORE INSTALLING, IT WILL LAST AT LEAST 50,000 OR MORE ROUNDS !!!!!!!

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    2. THE FINEST 1911 SPRINGS YOU CAN PURCHASE !!!!
      THIS WEIGHT HAMMER SPRING IS RECOMMENDED FOR PISTOLS FIRING FULL-POWER FACTORY / YOUR HANDLOADS. IT IS A REAL MUST WHEN USING FULL/REDUCED POWER RECOIL SPRINGS IN YOUR GM / COMM. SIZE FRAMES. FOR MOST CERTAIN INSTALL IN YOUR PERSONAL PROTECTION DEFENSIVE PISTOL !!!! TIP: POLISH THE INSIDE OF THE MAINSPRING HOUSING TO DEBURR, LUBE SPRING, SPIN-POLISH M/S CAP & M/S HOUSING RETENTION PIN. SMOOTHS COCKING EFFORT EITHER MANUALLY OR WITH THE SLIDE !!!

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    You're reviewing:Mainspring (Hammer) ISMI 19 lb