Lock bumping sounds like internet folklore until you see it done: a specially-cut key, a sharp tap, and a standard pin-tumbler lock opens in seconds — quietly, with no visible damage. It's a genuine technique, and it works against the cheap cylinders still guarding countless Manhattan apartments.
How bumping works (briefly)
A bump key is cut to maximum depths. Inserted and struck sharply, it momentarily bounces the lock's pin stacks to the shear line — and a turn of the key opens the cylinder. It requires a vulnerable lock and a little practice, nothing more. No drilling, no noise, no evidence.
Which locks are vulnerable?
Basic pin-tumbler cylinders — the kind in most builder-grade and big-box deadbolts — are the vulnerable class. If your deadbolt came with the apartment and looks generic, assume it's bumpable until proven otherwise.
What actually stops it
Bump-resistant designs: sidebar mechanisms, pin-in-pin (telescoping) pins, and rotating-disk cylinders all defeat bumping by making the bump physics fail. These are standard features of quality high-security cylinders — which is why a high-security upgrade is the real answer, not gimmicks.
What doesn't stop it
The fix is mechanical: a cylinder engineered against the attack, properly installed, ideally with a restricted keyway so overall key control improves too. Worried about your locks? We assess cylinders honestly — call (212) 671-0532 and we'll tell you what you actually have and what, if anything, needs changing.