One Spring Kit will include one of each: 

- ISMI 1911 Mainspring (Hammer) 17 lb
- ISMI 1911 Mainspring (Hammer) 19 lb
- ISMI 1911 Mainspring (Hammer) 22 lb

Work with Government & Commander Size Models

Work with Springfield Prodigy, 1911's & 2011's

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.

In independent testing, ISMI spring have endured in excess of 100,000 compression cycles. We don’t recommend going that long between changes however. With an ISMI spring, practice routine maintenance and change it once a year.

Frame Components:
Ignition Components
Ignition Components:
Hammer Springs
GTIN:
841370101245
Pin Selection:
Pin Set
Frame Components:
Mainspring Housing Components
Frame Components:
Pins and Pin Sets
Frame Components:
Springs & Spring Set