Bump resistance at least?

[Eyes_Only]

I've read and heard people asking if a lock can become bump key resistant if you put in "stronger" springs in the pin stacks and the answer has always been no.

I work in an automotive repair shop that does a high volume of tire work and we always have the floor littered with valve stem cores that come out of the "little rubber thing" you use to measure your tire pressure and add air. Well some longer valve stems have cores like this one, http://automotive-hardware.com/images/tire/17-490l.jpg It has a small spring in it if you can tell. So one day, instead of tossing them all out I gathered a few, cut them open to harvest the springs and loaded them up into my standard 5 pin mortise cylinder.

The result? These little springs are so strong that it takes about 10 to 20 times more effort to insert and remove a key and even my pick gun put on the highest setting couldnt open them. I wailed on it with the gun for 5 minutes and after giving up and releasing the tension, I only heard one pin stack return back.

I'm not claiming that this lock is bump proof but if my pick gun couldnt get this sucker open, would a bump key be able to do any better? Just wanted to thorw out this thought so maybe other people can give this a try and see how this turns out.

[linty]

you could also make a lock bump proof by filling it with krazy glue. :)

you'll run into problems with wear, people having to get their locks serviced yearly, which makes costly high security seem a more viable alternative i think.

[Eyes_Only]

It is impractical and by the looks of it it will probably wear out the key faster opposed to a lock with regular springs. But I thought it was a experiment worth conducting. Besides it couldnt hurt to share this with others and maybe this method can be improved on.

[Gordon Airporte]

It does seem that wearing down the key could be a problem, but you might be able to get away with some minimal number of these springs in the lock and the rest regulars, or maybe leave some out. If you keep the stronger springs in the last few pin stacks you'll wear the key less.
As far as I can remember, previous failed attempts to defeat bumping by mixing springs only used 'official' lock springs.

[Eyes_Only]

Well these are no official Lock spring. They're "heavy duty springs designed to retain 40 psi or more air pressure for automotive applications"