Security Pins: Spools, Mushrooms, and False Sets
Security pins are modified drivers or key pins that catch at the shear line when picked, bumped, or raked — resetting progress until tension releases. Mushroom, spool, serrated, and hybrid shapes appear in American, European, and Asian high-security cylinders.
Similar ideas extend beyond pin tumblers: serrated wafers and levers, false gates on disc detainers and combination wheels.
How Security Pins Work
When a pick lifts a spool or mushroom pin, its waist catches between plug and cylinder. The pin feels set but binds falsely until lightened tension drops stacks for a retry. Multiple security pins multiply false sets — the core defense against raking.
Pin Types
Mushroom pins taper at the waist. Spool pins narrow in the center like barbells; double spools are "barrels." Serrated pins add shallow grooves. Hybrids like "spoorated" spools combine features. Key-pin spools appear in Mul-T-Lock and ABUS designs.
Beyond Pin Tumblers
ASSA Twin uses serrated side pins. Abloy discs employ false gates. Medeco pins add anti-decoding rings and sidebar grooves. Security pinning is a system, not a single pin shape.
Limits
Skilled pickers learn to identify and defeat security pins through feedback and practice. They raise difficulty and time cost — the realistic goal — rather than absolute immunity. Pair with sidebars and restricted keyways.
Where You See Them
American Lock 1100, Schlage commercial cores, KABA Gemini, LIPS Octro, and many UL-rated cylinders ship with security drivers. Rekeying should preserve or upgrade security pinning intentionally. See pin tumblers and high-security locks.