bump key? is it for real?

Being very cynical the only mechanisms that would be free from bumping are those that have a slot in the tumbler and not two piece tumblers. I would narrow this further and consider the likes of Schlage Primus and ASSA (and derivatives such as Australian Lockwood Twin - now owned by ASSA-Abloy) vulnerable since a bump key can be made from one of the proper keys having the correct side milling for the cylinder to be bumped.

Bump proof mechanisms wuld be IMO be:

1. lever locks (including British Ingersoll - no relation to IR and Bramah)
2. high quality wafer
3. Abloy
4. Bilock - sidebars impinging on lower pins - no upper pins (pins and springs all in standard half inch plug).
5. Medeco - the sidebar impingng on the lower pins would defeat bumping.

No, both brands you list were tested and not opened using this method. The sidebar fingerpins need to be lifted to different heights, and turned in various directions for alignment. The sidebar pins do NOT have drivers, so the kinetic energy transfer prevents opening rather than assist it.

Look farther down to the original discussion "An interesting link" where there is a report.

1. EVVA 3KS.

Be that as it may, if a bump key is made from a key intended for that suite of cylinders eg a stay university campus key, then the bump key will set the finger pins correctly when fully inserted. Success would depend wheher the sidebar beds in and the plug can be turned before the drivers descend. Alternatively whether there is sufficient slop in the sidebar aspect to enable the drivers to be caught before the sidebar beds in.

It would require more care and would be less predictable than for ordinary cylinders, but the potential is there for success.

By the way, this is the first I have heard that the finger pins are angle dependent like the 'small' Medeco mechanism - is this right?

Hello,

Yes, Schlage Primus has left/center/right and high/low. The small distance of 'slop travel' involved with alignment combined with driving the key into the lock to bump standard pins, makes bumping with the correct sidebar cut bump key much like playing a lottery that only pays off if you get all the numbers - good luck!

- David

I have been a locksmith for 32 years. I now use bump keys all the time for opening and rekeying those pain in the butt schlage levers.It works great!. Sometimes I can open the locks withing a few seconds