Gunner, thanks for the lead on my new quest!
I just found a 520 (marked Ranger, not Stevens, but same thing) and walked home with it for $100! The gun is in fantastic shape, I'd say at least 80%, not bad for a gun that's about 100 years old. Great bluing, good trigger and very tight action, polychoke and it has the old model suicide safety.
Funny thing is that I've been trying to find a "trunk gun" in 12 gauge, since most of my hunting guns are 16s - I figured a 12 ga would make more sense as a spare, since I can't always find 16ga ammo, and would be SOL if something happened on a hunting trip (or I just forgot to bring my ammo). My favorite gun store is now LOUSY with 16 gauges, including a 520 and a decent priced 745 (the copy of the A5) - but he had no "cool" 12 gauges. All they had was tacticool stuff that I can get anywhere. I like my gun to stand out in the rack as different, and I think I've succeded.
Now to find disassembly instructions.