Master key pins maybe?

[Gregted]

Just picked one of my freebees from the locksmith clean out and found these small pins/wafers on top of the key pins.

They were only above pins 1,2 and 3.

Pin 1 is 1.51mm

Pin 2 is 0.74mm

Pin 3 is 1.50mm

I have read about master keys and assume these are the very same extra pins.

No name on anything but AT30 above keyway and R on left and 3 on right of keyway.

http://s270.photobucket.com/user/spook0 ... s.jpg.html
http://s270.photobucket.com/user/spook0 ... e.jpg.html

[mechanical_nightmare]

Those are definitely master pins. I do not know about the numbers and symbols stamped onto the lock, as the manufacturer and their keying system is unfamiliar to me. I am sure somebody on the site will know though.

Welcome to the forum btw!

[ARF-GEF]

In the bygone days big companies sometimes also labelled their masterkeyed locks themselves to make service stockkeeping and control easier. It doesn't really seems too logical to me but I guess when you had like 400 locks to keep track of with paper tracks in the 1960's and service and follow them on the boxes this was an option.
I have seen similar markings on those locks, though not on the plug.
That is my idea, but it's only a wild guess.

Yes, welcome, welcome