Waterbury US Set. Jerk bitting.
Definitely a little rusty, but it works well enough. My first thought was, "Dirty lock, might be a little challenging." Then I removed the key saw the narrow keyway and the bitting some jerk gave it. I thought, "Ooh, now this could definitely be interesting!"
The keyway was probably the most challenging obstacle. I had to use the one wrench in my kit that I absolutely hate. I use Southord slimlines, and even then only my smallest hook would fit. I figured that might make avoiding an overlift of the front pins rather difficult; but as it turns out, not so much. It ended up being somewhat anticlimactic in the end, but it's still a neat little lock, and the only one I currently have with that sort of keying.
Kind of curious if any of you folks have run into other Waterbury padlocks with this sort of bitting.