need advice bore gauging top break

bobsdad

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Does anyone have advise regarding the correct method for measuring the bore, and cylinder/cylinder throat gauge on the safety hammerless or top break types? I have one in rather good condition and would not like to damage it, but would like to know dimensions when order cast bullets. I did a search of this forum but did not find anything relative. Thanks in advance for any advice.
 
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A set of small hole guages and an ordinary outside 1" micrometer will do the chambers, throats, and bore. Groove dia.( the usual cast bullet dia.) normally requires a Cerrosafe cast.

You can also use Cerrosafe to make a chamber and throat casting which can be measured with the mic. However, you would need to cast all 6 chambers to be certain of the dimensions. This would eliminate the requirement for the small hole gauges, but it is a bit more tedious to make the castings.

LittleMachineShop.com - Small Hole Gage Set, 4-Piece Starrett

Cerrosafe Chamber Casting Alloy 1/2 lb - MidwayUSA

WOB
 
You can also use a soft lead slug to tap through the bore. Usually the capability of accuracy of these older handguns isn't enough to show the difference. I just use the standard diameter for the caliber.
 
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