ISMI springs to tune your 3.9 inch P320 models for compensators and suppressors. Only compatible with our guide rod for the M18 and XCarry pistols.

The factory spring weight is approximately 18 lbs. All of these springs are reduced power springs and 12 lbs is the lowest spring weight that the firearm will run on. We do not recommend using a 12 lb spring for suppressors. 

Guide Rod for M18/XCarry