STI and Staccato 2011 magazines are the standard for USPSA Open, Limited, and Carry Optics competition — and the springs inside them are doing serious work every time you slam a 140mm or 170mm tube into a wide-body frame under pressure. Open division shooters running 170mm magazines at 28-plus rounds push springs through more compression cycles per match than nearly any other platform in competitive pistol shooting. Spring fatigue in long-tube magazines shows up first at low round-counts within the mag — the last few rounds where spring extension is at maximum and follower angle is most critical. Carry Optics and Limited competitors running 140mm magazines face similar issues as round counts accumulate across a season. Replacement springs for STI/Staccato 2011 magazines are a critical maintenance consumable, not an optional upgrade. Match-ready magazine kits should include fresh springs before any major match. Compatible with standard STI/Staccato tube bodies in both 9mm and .40 S&W configurations. Keep a full set of spares in your range bag. Fast same-day shipping on most orders at Shooters Connection.