My nightmare (modified Yale)

[scriptguru]

It's a little bit strange why major manufacturers don't make serration or threading on the bottom chambers - it would make locks way harder to pick, and they would add more stars to their "security rating". It's quite a simple idea in conjunction with serrated pins, and quite cheap to do, especially in comparison with other things they do with locks to make them more secure.

[MrScruff]

Sorry if this is a silly question but I'm sitting here with a question mark hovering over my head... wouldn't serration in the bottom chambers increase the possibility of troubles when inserting the key? I'm imagining grime or general wear and tear when I say this.

[scriptguru]

Perhaps, it depends on the shape of pins and chambers. I believe it's not that hard to do that pins would slide easily when just inserting key, and not easily when the lock is picked (under tension).

[femurat]

The average lock user may apply some turning force while inserting or extracting the key, hence more wear in the serrated pins and chambers... and some broken keys!

[MrScruff]

That slight turning force is what I was wondering about. I've seen people do some pretty ridiculous things to locks on a good day so it makes sense that they could cause unintended effects. Now that I've had about 24 hours to think about this though, I'd love something like this on my doors.

[scriptguru]

Maybe two non-serrated pins in two non-threaded chambers would solve the problem.
But there are additional conditions:
1. That must be first and last pins (nearest and deepest), to make sure the plug will be positioned right under torque.
2. Ideally they should be positioned slightly differently to other pins, to make sure that under torque they touch the lock internals first. However, even without condition 2 it would work quite well.

Unfortunately, pin tumblers still have weaknesses to force attacks (for example, it's not that hard to use hard metal screw to break plug apart and then open the lock manually), so I would not use such improved lock - it is already obsolete IMHO. I love pin tumblers, but I believe the industry should move forward. On the other hand, as an imrpovement to existing locks it would be not bad at all.