William T. Watts
New member
the gauge has 6 groves cut .298" .299" .300" etc
Frankenmauser I have a Scott A. Duff bore gauge that is tapered from .298-.303, the gauge will measure the diameter from land to land, a perfectly cut bore will measure .300" with the opposing lands measuring .004" combining the two land and bore measurement they total .308' which would be a perfectly cut 30 caliber bore. Usually gauges like mine are/were used to check bore wear for 30 caliber military rifles when then were sent to their armorers for rebuild or maintenance. The gauge usually works well with most 30 caliber barrels with exceptions like the Marlin micro grove barrel and yes it did measure .3022. The gauge is not difficult to read and I've used it enough to determine within .0001" plus or minus which is good enough for me. I am a graduate of Trinidad state gunsmith program 2001, no I've never worked as a gunsmith, heart disease and the stock market tanking while I was enrolled in school prevented me from opening my shop plus a large student loan that had to be repaid.. I still have all my tools and I work on my own guns but never put in the shop I wanted.. FWIW google Scott A. Duff publications, his Address is P.O. Box 414 Export, Pa 15632, I have no idea if he still sells these gauges or not but mine was purchased at least 15 years ago!! William
Frankenmauser I have a Scott A. Duff bore gauge that is tapered from .298-.303, the gauge will measure the diameter from land to land, a perfectly cut bore will measure .300" with the opposing lands measuring .004" combining the two land and bore measurement they total .308' which would be a perfectly cut 30 caliber bore. Usually gauges like mine are/were used to check bore wear for 30 caliber military rifles when then were sent to their armorers for rebuild or maintenance. The gauge usually works well with most 30 caliber barrels with exceptions like the Marlin micro grove barrel and yes it did measure .3022. The gauge is not difficult to read and I've used it enough to determine within .0001" plus or minus which is good enough for me. I am a graduate of Trinidad state gunsmith program 2001, no I've never worked as a gunsmith, heart disease and the stock market tanking while I was enrolled in school prevented me from opening my shop plus a large student loan that had to be repaid.. I still have all my tools and I work on my own guns but never put in the shop I wanted.. FWIW google Scott A. Duff publications, his Address is P.O. Box 414 Export, Pa 15632, I have no idea if he still sells these gauges or not but mine was purchased at least 15 years ago!! William
Last edited: