I have a Comp-Tac MTac IWB hybrid that I use carrying my Glock 23. I know the OP specified outside the belt, but I don't find the G23 to be too large to have inside my waistband.
This holster has served me very well and has the added benefit of being able to change guns later if you purchase another pistol. The Kydex bodies are available for a whole bunch of guns. The leather has molded to my body and makes this a very comfortable holster. They run around $90 plus shipping, so they aren't cheap, but I feel it is worth every penny.
I have carried with this rig in pretty much any/every attire from full winter gear (in NC) to shorts and a tshirt in the summer and been well concealed and easy to carry and draw.
Of course, your mileage may vary, but that is my .02.
Ruffinig