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Mainspring (Hammer) ISMI 17 lb
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Mainspring (Hammer) ISMI 17 lb

Product #: 10640
Price: $6.49


In Stock
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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

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