LearningToPick5 wrote:The best explanation that I can come up with is that the holes in the bible are slightly misaligned. So when you set one pin, the core rotates extremely slightly which then sets another pin - and maybe it's this slight rotation that makes a click. But this seems like a design that wouldn't be necessary for a key. Can anyone explain this?
That's basically it, plus that the pins themselves are not exactly identical. There are small variances in the manufacturing of the parts, and wear can add further to this over time when the lock is used. The pins don't fit tightly into the holes either, they need some room or they would seize up with temperature changes or even tiny amounts of dirt. Since they have variable lengths, they "tilt" in slightly different angles in the holes when you put pressure on the core, which also changes the way they bind.
This all said about "standard" pins which are just straight cylinders. When you add "security" pins into it, i.e. pins with different shapes, like spools, it's more obvious that they will bind in different ways. They are somewhat of a two-edged sword against picking. While they make certain types of low-skill attacks like raking and bumping much harder, they can actually make single-pin picking easier for a skilled lock picker (to some degree at least), since they give more feedback and more distinct sets.
I have some old ASSA locks with just 5 standard pins which are annoyingly difficult to pick due to just high precision in the manufacturing. Several pins bind at once, and when you set one or two, they tend to drop down again when you set another. Very frustrating. One of them is much easier to rake than to single pin pick.
