They are the same as 1911 screws. They are 0.150-50. If you have factory Kahr wood grips, the 1911 "thinline" grip screws "might work"...or you could get the standard 1911 screws and shorten them a "little" bit.
Look here as this is the cheapest place I have found to date and fast shipping to boot.
http://www.woodgrips.com/screws_&_bushings.htm