Bore Gauge

[Kensal Rise]

I'm not sure what you mean by "bore gauge." If it's "choke gauge" then the Galazan is a good choice for plug guages. But... remember that the amount of choke is the difference between the actual bore diameter and the muzzle/choke diameter. Thus, a plug gauge can only suggest choke. A micrometer dial gauge can measure it.

[Neil Richardson]

To be a little more specific:

This is the Galazan gauge ($450):

Professional Choke and Barrel Gauge -The world standard precision instrument used by gun manufacturers and barrel makers to measure bore diameter and choke constriction and length. This gauge is a must if you expect to be able to determine if chokes and or barrel bores have been altered. Dial indicator measures in .001 increments. Measurements are detected by expansion and contraction of three metal "fingers" under the control of the person taking the measurements. All test and set bushings and instructions included. Comes with a handsome wood case. Gauge length 22 3/4" weight: 1 1/4 pounds

This is the one on Brownells:

CSP PROFESSIONAL SHOTGUN BORE MICROMETER SET ($509)

Brownells also has SKEETS SHOTGUN BORE GAUGE $93.99