Nonsensical key question

[Rich_NYS]

PO gave me two keys; one appears to be original, one is a cut key.

He mentioned the original works for both the door & ignition, the cut key only works in the door. That made no sense to me, so [of course] I tested the cut key and it works as I expect it would in the lock & ignition.

The one theory I have is that maybe the cut key was a sloppy cut, off a bit, and [at first] only worked in the door. Possibly, over time the keys & locks became a bit worn & now the cut key works fine.

The question: is there another legit explanation as to why the cut key would only work in the lock? I'm also wondering how well a key cut from code will work in the locksets that might've become worn over the years.

[rdarlington]

The parts of locks that wear are usually made out of pretty hard materials so it takes a very long time and a lot of abuse to wear them down. They do wear, just much more slowly than the key. It's easier to cut a new key than it is to service the lock.

It's more likely the cut key was off by a bit and the PO had to jiggle it to get it to turn over in the ignition lock but not the door. The tolerances in locks aren't exactly that tight, but quality locks are tighter than say your typical Kwikset lock and you'd see this happening more in those.

I've seen many times that over the years an ignition key will wear a lot more on one side than the other due to how it's on a keyring and how the person using it inserts it. Try inserting your key with the other side facing you and see if you have issues.

[DCUK Martin]

The door locks have fewer tumblers than the ignition. They only "read" the rear 5 IIRC whereas the ingition has more right to the tip.