Have you got any 3 in 1 oil? Drop some into it, just a little and repeatedly insert key and work the lock to spread it about.
It may just be dried up and sticking.
It should not be oiled.
Don't leave a key in the keyhole.
With the key in on the inside, it prevents a key being used from the outside.
The cylinder sticks out on both sides! When I originally replaced many years ago, I replaced like for like.
I had no idea it should be flush!
The amount it sticks out on both ends, I would say is 10mm!
See pics below.
a housebreaker can turn the key from the other side with a simple tool to unlock the door.
or, of course, break glass and open it.
in an emergency, an honest person trying to open the door will be unable to.
there is (at least) one.Not sure a simple tool would do it.
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