xrrcr Posted September 29, 2021 Share Posted September 29, 2021 I have 6 different 9mm's, all with varied oal requirements. Bought a throating reamer to standardize them. Problem is how to measure the depth of an angle at a particular diameter. Tried optically and that sucked. So came up with this and wanted to share. Starting from the left, that is a .3540" gage pin. It slides inside of a turned aluminum sleeve that mimics a case in the chamber. The pin slides all the way in flush with the sleeve, so that the indicator can be zeroed. Then you insert it into the chamber and a measurement from the case step to the .3540" datum line is given. My particular chambers ranged from .125" to .062" using this method. Link to comment Share on other sites More sharing options...
Jim Watson Posted September 29, 2021 Share Posted September 29, 2021 I could see a market for that, and a guideline for measuring the bullet ogive to see where they clashed. Link to comment Share on other sites More sharing options...
ltdmstr Posted September 29, 2021 Share Posted September 29, 2021 Plug the barrel, stuff a piece of clay in the chamber end, then pop it in the freezer. When it gets hard, remove it from the barrel and measure. You can also do a chamber casting with cerosafe. Link to comment Share on other sites More sharing options...
xrrcr Posted September 29, 2021 Author Share Posted September 29, 2021 I want to use it as a comparative measurement tool not absolute. Needed something to keep track of where I was during throat reaming. Make them all the same and then ultimately make a stub gage to use for plunking new bullet profiles. Link to comment Share on other sites More sharing options...
zzt Posted September 30, 2021 Share Posted September 30, 2021 I use a Go gauge and new Manson reamers. They provide a .055" throat. That's long enough for any OAL I load. Having a longer throat than needed for a particular ogive does not affect accuracy. I have a Brazos Custom 9mm barrel. He uses a .100" long throat. The barrel is super accurate even though I only load to 1.161" with HAPs. Link to comment Share on other sites More sharing options...
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