different type of security pin

[Fredo the Crow]

Winkhaus also use those barrel pins (amongst other niceties and naughty keyways) as seen in this picture borrowed from their official site:

[cj101]

Abus uses these pins, as well as serrated pins now extensively. But not in a pure barrel form, but as a combination mushroom pin with a reduced diameter end. So a combination of both of them.
The EC550 uses torpedoshaped key pins as well. The other locks form them use serrated keypins and keypins with reduced diameter as well.

To pick these locks, I use a combination of soft raking (very little pressure) and normal pin by pin picking. If I set a mushroom pin, I try to set all other pins a bit and rake a bit.
The binding order is in my opinion, however, not altered by these pin, as there is a hard edge below the reduced diameter end. The tolerances of the lock itself are, nevertheless, not the best. This could, of course, change the picking behaviour.

[Shifty1]

I know my response is a bit dated to this post but I have an old Yale rim cylinder 5 pin lock chock full of mushrooms with a "sneeky pin" just as you describe. Honestly, this was the first security pin lock I ever picked. I've been wrapped in locksport for about a year now and this old lock gives me lots of practice even though I pick it easily now. I've gutted this lock and I know the pin stack location where the sneaky pin resides(at #1 and a short one too) but honestly the whole lock pinning was such a balancing act to pick to begin with that I was hardly aware of the different feedback I was getting when I had first hit upon this style of key pin. In fact when I first attemped to pick this lock I could not pick it. I had heard of security pins but had never encountered one much less four! I did'nt even know what a false set was! Now a thousand hours later... I'm a better picker partly for having found this lock, and this forum! Boy this lock must date back to the late 40's or early 50's. And the it occured to me from reading somewhere that this style of pin would be an anti-impressioning key pin primed to false bind. I have yet to impression this old dog to test my theory just because its in too nice shape to get rough with it! Nevertheless, it's intresting to see how far back in time a layered security approach became implemented in pin tumbler design.

Cheers!