Here's my 5" Mil-spec riding in Gary Brommeland's MaxCon V. The cover shirt is size medium, same as I wore 20 - 30 pounds ago. I'm currently 5'-11" and 190lbs.
I'll soon be switching my primary carry to a Glock 19 in a Brommeland Def Con OWB holster - just picked it up yesterday and it was a sweetheart at the range

(pics coming Monday).
Going to OWB carry I've bought several size large shirts just to add a little length to the cover shirt. The mediums will work fine for normal situations but for reaching top shelves at the store I wanted the extra coverage.
Jack