Well not rare, this is an uncommon configuration for a Ruger GP100. The barrel is 4", not 4.2" and has a half-length ejector rod shroud. And it's a fixed sight model. It's a model 1711 (KGPF-340), and was made around 2011. The beveling on the fixed sight, plus the half lug make the frame look a lot less chunky than a typical GP100 (though the stock Hogue grips don't do the looks any favors). It has probably between 1-2000 rounds through it.

Be aware I use gmail, so I don't get any forum notifications. I will check for messages a few times a day though and try to be responsive. I am not that interested in meeting outside of Loudoun.