What are security pins (Sicherheitsstifte), and how do they defeat picking?

Security pins have non-cylindrical shapes — spool, serrated, mushroom, T-pin — that catch on the shear line in misleading ways, creating a false set that fools the picker into thinking they've set the pin when the lock is still locked.

The false-set trick:

Normal pin:                Spool pin (security):
Sets cleanly when           Sets at the WAIST first →
driver/key boundary         picker thinks pin is done →
hits shear line             plug rotates slightly →
                            pin then catches at the SHOULDER →
                            plug stops, picker is confused

The four common security pin shapes:

How a skilled picker handles them:

When a security pin false-sets:

1. The plug rotates noticeably — feels like progress.
2. Other pins seem to be set — but the lock won't open.
3. The trick: release tension slightly — the false-set spool drops back to its waist position.
4. Push the spool pin further up past the false-set zone.
5. Re-apply tension — find the next binding pin.

This is called counter-rotation or negative tension and takes hundreds of hours of practice.

Why high-security locks pile them up:

Premium cylinders (Medeco, Abus Granit, Mul-T-Lock) often have all pins as security pins — a mix of spool, serrated, and T-pin shapes. A picker must counter-rotate through false set after false set, and each error resets progress. Picking time goes from seconds to hours.

Tip: For a few CHF more, cylinders with anti-pick pins (look for "anti-pick" or "Sicherheitsstifte" on the box) raise the picking time-to-open by 10–100×. Worth the upgrade for any door behind which you store valuables.

Go deeper:

• Pin tumbler lock — security pins — diagrams of the spool and serrated shapes and the false-set behaviour they create against rakes and pick guns.