I'm kind of a skinny old fart, and I usually wear blue jeans and a tee shirt, so concealment can be problematic.
My favorite carry gun is a Smith & Wesson 642 revolver with CT laser grips...Light, durable, dependable, and VERY easy to conceal in a good pocket holster.
When I get duded-up and need something even more concealable, I pack a little Kel-Tec .32, also with a CT laser. Granted, it's a mouse gun, but it's WAYYY better than the Kimber that's sitting at home because I can't hide it easily.
I choose it because of the price (deal I got) and comfort. I have a Ruger P94, S&W 586 but the PPK conceals nice and doesn't jab or stick me. I sometimes forget I have it on.
I believe the question was:
What is IN your CCW pistol?
BTW, I too have an Interarms Walther PPK and it is very concealable - I use Speer GDHP ammo because truncated cone type bullets like the Hornady XTP .380's don't feed reliably in this gun.
Guns Have Only Two Enemies-Rust and Politicians "The United States Constitution (c) 1791 - All Rights Reserved" If Guns Kill, Do Pencils Mis-spell Words? Pain is Weakness Leaving the Body - USMC "Qui desiderat pacem, praeparet bellum"