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03-17-2022, 01:42 PM | #3 | |||||||
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Bruce A. Hering Program Coordinator/Lead Instructor (retired) Shotgun Team Coach, NSCA Level III Instructor Southeastern Illinois College AMM 761 |
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03-17-2022, 04:11 PM | #4 | ||||||
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Bruce, I most certainly agree with Randy. It is seldom that my gauge measures exactly .729. I don't know just when Parker stopped overboring, but my older guns -- hammer guns and hammerless -- as I recall have larger than current nominal bores. Some may have been honed somewhere down the road, but I still think older guns are likely to have bores larger than .729.
Do you know the wall thickness at various points of the barrels? I like to know those more than the diameter. If you were closer...
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03-17-2022, 05:07 PM | #5 | ||||||
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Duplicate post
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03-17-2022, 05:08 PM | #6 | ||||||
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More likely than "been honed" would be "your micrometer isn't quite accurate" or "you didn't quite measure correctly". No big deal, that's just the way it is. What brand of micrometer are you using, or is it a micrometer at all? I'm guessing your bores are just fine.
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03-17-2022, 11:31 PM | #7 | |||||||
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__________________
Bruce A. Hering Program Coordinator/Lead Instructor (retired) Shotgun Team Coach, NSCA Level III Instructor Southeastern Illinois College AMM 761 |
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The Following User Says Thank You to Bruce Hering For Your Post: |
03-17-2022, 05:58 PM | #8 | ||||||
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If someone was to shop for a tool to measure this on the used market, what is the best tool?
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03-17-2022, 06:53 PM | #9 | ||||||
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For my money, Hosford's gauges hands down. They are expensive but they are incredibly accurate. His bore/choke gauge uses tiny collapsible fingers (3). I have run some comparison tests against a c. 1970s ball gauge which uses 3 small spheres on the brass head, which has proven to be very accurate. The range between the ball gauge and the Hosford gauge has never varied more than .003-.005 for the some 50 guns I have measured with them. No mystery using his instruments (he also makes an incredibly accurate barrel wall thickness (BWT) gauge.
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03-17-2022, 08:28 PM | #10 | ||||||
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Austin H. put out an analysis of 12 ga. bore diameters on this forum years ago. He found that prior to S/n 70,000, there was a distinct "node" or cluster of guns bored .750-.755 , with a lesser node in the .730-.735 range. After 70,000, the large diameter node disappeared. I am attaching what I copied from his post back then.
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