The extended magazine spring is designed to replace the factory-supplied spring for compatibility with aftermarket magazine extenders and extended base pads, thereby increasing the magazine's round capacity. It provides the follower with up to 10% additional power, ensuring smooth and reliable feeding of rounds. Constructed from certified aerospace-grade chrome silicon wire, the spring undergoes heat treatment and stress relief in accordance with ISO 9000 standards.

Compatible with Smith & Wesson M&P pistols, accommodating calibers of 9mm, .40 S&W, and .357 Sig

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It is the customer’s responsibility for understanding state laws regarding all purchases made. For a comprehensive list of all Shipping Restrictions, please refer to our Shipping Restrictions By State Page found Here.

All NFA Rules Apply

These items are controlled by the U.S. Government and authorized for export only to the country of ultimate destination for use by the ultimate consignee or end-user(s) herein identified. They may not be resold, transferred, or otherwise disposed of, to any other country or to any person other than the authorized ultimate consignee or end-user(s), either in their original form or after being incorporated into other items, without first obtaining approval from the U.S. government or as otherwise authorized by U.S. law and regulations.

It is the customer’s responsibility for understanding state laws regarding magazine capacities. Palmetto State Armory abides by all state regulations regarding the sale of high capacity magazines. We DO NOT ship high-capacity magazines with firearms to certain states. We WILL NOT replace high capacity magazines with state compliant magazines. We DO NOT offer refunds in place of the magazines. Please see our terms and conditions for a list or restricted states.