Go with the Skeet's. It's way more accurate than most of us will ever need. And it is very portable, fits easily in a briefcase--think "gunshows". My gunshow tools are: Skeet's bore gauge, wall thickness gauge, Galazan chamber gauge, electronic fish scale, tape measure, magnifing glass, and snap caps. All fit into a light aluminum case. Might sound like overkill but it has saved my butt many times. It is amazing how many bores and chambers have been fiddled with and safety issues are only revealed with the gauges. Undoubtably the best portable wall thickness gauge I've found is sold by Jonathan Pool of Fine Firearms, (619-280-8600).
