I got a Black & Decker deadbolt recently to practice on, now I'm not sure but I think it's defective and it's definately hindering my picking practice.
One side of the bolt (this one's a double cylinder but the two are held to the door with about 5" long screws, now it's not mounted to a door or a piece of wood so I don't know if the fact that it's not bolted to a door and therefore not held very well in place, that may be why it's not locking) won't lock but will unlock, one side will both lock and unlock. Note that this is using the key on either side and this was happening before I ever picked it.
I've also noticed that on the side that doesn't unlock, it seems to get stuck at about a quarter turn to the right,
I'm unsure whether or not the distance between the two cylinders affects how the locks work, because unscrewing the screws a half inch and pulling the defective lock back seems to make it work once in awhile.
Now I re-pinned the defective lock to include only one pin, to work with digital blue's exercises and it still has the same problem when picking.
Any suggestions?