doublegunshop.com - home Forums General Discussion DIY Gunsmithing @ doublegunshop.com Skeets Bore gauge

Thank you for your replies. I have changed out the dial indicator for another higher-end digital indicator that I have as surplus. Indicator is a friction fit and pulls out quite easily. As this unit did not come with the calibration ring I have used a quality choke tube of known diameter +0.700 for calibration. This appears to work quite satisfactorily.

Be super careful in the calibration if the .700 portion of the choke is not a flat section. Measuring the tip of the choke is very ticklish. Gettin the round balls of the gauge exactly aligned with the end of a choke taper can make you cry sometimes. Doing that for calibration will be delicate since the rate of change of the reading is very high there.

Just spend the money and buy a set of real calibration rings. If you know of a precision machine shop close by, ask them to make you a set of calibration rings.

https://100straight-com.3dcartstores.com/Single-Ga-Ring-Only_p_32.html

I think most of us can figure out whether the bore or choke we are measuring is round or not. Your measuring ring can be proven accurate by comparing with any known bore. TIRS.

I have a 100straight Choke & Barrel Micrometer, 4 Gauge Regular Set. They work well, even in the .410. I bought mine off EBay for less than half the retail price. Need to upgrade to a digital gauge for ease of use.

I had bought one on eBay many years ago and it wasn't working correctly as sometimes the dial would stick. I called and talked to Dean and he said send it to him. He had been making a longer version that was 16" long and I asked if he could fix mine and add the new 16" rod. When I got it back I swear it was a brand new one, new dial indicator, long 16" aluminum rod. I forgot what he charged me but it was very, very reasonable.
I have since made a wooden case and also made a .600 ring for 16 gauge. I tried making a head, not so easy as the holes for the ball bearings have to be the same as the diameter of the balls. Maybe I'll try again and this time I will use a piece of scrap aluminum.

Bill is right about using a small bore gage, I have a set when from long ago that goes to 1/2". Better using this than a snap-gage.

The 2 head gauge I purchased through Brownells came in a box that had provisions for storing the calibration rings and the second head and storage ring. The storage and calibration rings are very close in size. The calibration rings were normally kept in the box since you generally need them only when switching heads. I have always presumed that the protective rings were intended to store the unit with the balls off the seats to prevent sticking and rough action.

If you ever manage to "disassemble" one of the heads, you have a tedious job ahead. With the way the balls and actuator fit into the head, the only way I could get it back together properly was use grease applied with a toothpick to hold the balls in place. This followed by insterting the polished balls and rod. Not something I ever want to do again.