MEC Spring

The MEC Spring (SKU ME330) is a precision replacement component engineered for reloading press systems manufactured by Mayville Engineering Company. Though diminutive in stature—weighing just 0.01 lbs with compact dimensions of 3.45 x 0.75 x 3.55 inches—this spring serves as a critical control element in ammunition reloading machinery. Since MEC's founding in 1972 and the subsequent production of over 30 coining and spring machines, genuine OEM replacement parts like this spring have remained essential consumables for serious reloaders maintaining consistent press operation and reliability.

The MEC Spring functions as a tension and return mechanism within MEC's reloading apparatus, controlling spring-loaded operations that index components, cycle primer feeds, or manage shell plate advancement depending on your specific MEC machine model. Springs in reloading equipment experience high-frequency compression cycles and material fatigue over extended use; replacing a worn or weakened spring restores the precise actuation forces needed for consistent primer seating depth, powder charge metering, and overall shell processing accuracy. OEM springs ensure metallurgical specifications—hardness, fatigue resistance, and tension characteristics—match the original engineering tolerances of your equipment, preventing premature wear on adjacent components and maintaining the repeatable quality that reloaders demand.

This replacement spring is ideal for operators running any of MEC's progressive or single-stage presses who notice sluggish indexing, inconsistent primer feed, or diminished spring resistance in their machines. Before ordering, verify your specific MEC model—whether a 600, 650, Grabber, or Sizer—against the MPN 330 designation to confirm compatibility with your press configuration. Installation requires minimal mechanical skill; the spring typically mounts to a fixed pin or post within the machine's frame. Keep this part on hand as preventive maintenance, since spring failure can cascade into missed primer feeds or shell misalignment that ruins loaded ammunition and halts production until the machine is serviced.