doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Skeets Bore Gauge - Accurate?

Temperature does affect metal, but most intruments made are not that close in tolorence to worry about.

When I was much younger and worked in a model shop all the technicians in the inspection department, wore cotton gloves not to keep their hands warm, but as Miller said to not increase the size of the objects being measured. The room was also climate controlled. Some of the dimensions were to very close tolorances and were measured using an optical comparator, which can magnify the object quite a bit for measuring.

My measuring ring set on the $495 Galazan bore gauge is "heat sinked" as purchased. You zero in the ring, measure the gun immediately after. I don't think I will experience a variation of more than .00001 that is related to temperature. I spent 5 1/2 years in an instrument shop in an earlier life, understand close tolerances, but measuring a shotgun bore is not rocket science and a thousandth or two does not change safety level or value. By the way, the $495 single head Galazan gauge (not the interchangeable head model) is the only gauge I am aware of on the gun market that will measure tens and eights. It's maximum measure seems to be .900, plenty for the biggest eight gauge bores. I have not confirmed the accuracy of the .900 measurement, but will as soon as I can get an accurate zeroing ring at close to that dimension.

Bill, Let me know what size ring you need and I will make one out of aluminum and could give it to you at Carlisle in March.

Also if you have the 100 Straight bore gage, the one that comes with 4 interchangeable heads, and I believe you can order them with a 10, 12, 16 and 20 ga. or whatever combination you like, for the same price. You can also get the shorter length or the length that reaches 16".
If you have this set, you can also order other heads and setting rings for under a $100.
I am wondering if Galazan's set is from 100 Straight.

A proven ring of .835 to .865 would be suitable to zero the one head Galazan gauge for eight gauge and big ten gauges. The biggest ring that comes with the gauge is .775, the nominal ten gauge bore dimension. .835 would be the nominal eight gauge bore size. I measured a cleaned up eight gauge this weekend by checking the gauge at .835. The bore measured .900 on the gauge, but I'm not sure the gauge is accurate above .775. I need a bigger ring to check on that. Whatever you can do would be appreciated.

I'll make you one of each, .835 and .865.

Bill, or anyone, what is the bore diameter of the old ten gauge bores pre-1900. I thought they were also .775 but some think they were closer to .800 for the old shells fiber wads.

I have two Syracuse 10 ga. L.C. Smiths, one a 1884-5 hammer gun and the other a 1886 hammerless and would like to know bore. My 12 Skeet's gage will not go that large.

Yeh, thanks Larry and Bill for pointing out the obvious. Kensal's and my and Ian's point concerns a special case in which direct reading of RELATIVE constriction is accomplished quite easily without setting to say a .7 ring gauge, sleuthing out the fact of .729 or .725 or .742 main bore and then having to remove a shoe or so to deal with the real starting point when any arbitrary start will yield the same result. I like big macro hash marks for choke and for choke only. Perhaps this special case is also obvious; should be after chewing the same cabbage over and over and over. I should add that there are a host of pretty savvy guys out there who think one of those brass shoulder gauges tells all honestly. Avoiding actual measurements by the method mentioned sometimes rings a little bell for them and they get beyond the "nominal" constriction and the gauge standard bore. Mensuration is also useful for determining other info about the old sewer pipe.

jack

OH! Mensuration. I was headed for the gun room for some Hoppe's #9 and rags.

Really?

I wouldn't say that anyone who thinks one of those drop in, brass shoulder gauges "tells all honestly" is very savvy at all. You don't need to set the ring on a dial-type bore/choke gauge in order to measure constriction. However, the drop-in gauge only tells you constriction based on standard bore diameter. Anything differing from standard--and I've read bores that differ close to .020 from standard--will give you a totally inaccurate reading.

Amen to that Larry, without knowing bore size, a choke gage is useless. Might as well use the dime for 12 ga., it would be the same.