I've never been fortunate enough to pick a W keyway. I've picked the majority of the best alphabet, except for Q, some of the T's, and all of the W's. I think this one is an S, but it's hard to tell sometimes without actually trying a key in it.
This is one of the posts that Engineer mentioned, where johnopsec talks about using a small GOSO pick to get around in the keyway of a Keymark SFIC.
http://www.lockpicking101.com/viewtopic.php?p=319456#p319456Making the tools you have work for you is important, but for a tough keyway making or modifying tools to fit better definately has it's place and it is a cool feeling to defeat a lock with tools you made. Anyway, it's a great looking core. Mean keyway, but if you get a hook that helps you find more room to work, then it should just be a matter of time.
-ToolyMcgee