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Old February 12, 2013, 05:55 PM   #1
Join Date: July 25, 2008
Posts: 45
Help identifing item


I am trying to identify a tool or something I got when I bought out a gunsmith

The large outer ring in 1 X 1 inch and has tick marks on the right side where it tapers. It is .694 ID and 40 TPI the whole length.

The inner barrel is .7135 OD and again 40 TPI. It is 1.13 long and has a set screw and a locking ring. There are two inner diameters; .437 under where the set screw is and .576 for .540 inches on the other side.


Last edited by Tom-C; February 12, 2013 at 07:31 PM.
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Old February 13, 2013, 12:22 PM   #2
Join Date: March 4, 2005
Location: Ohio
Posts: 14,058
I expect this is some kind of calibration knob for a female 40-tpi thread that surrounds an adjustment shaft for the set screw to hang onto. It might be used to adjust a seater stem or a powder measure or any of a number of things.

As a knob, the knurled ring probably works as a jam nut to fix the position of the larger ring or drum at some point of calibration. If there are 25 graduations on the drum, then, once jammed so it turns the whole thread, they represent 0.001" per graduation of depth change into whatever female thread the other end engages.
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Old February 14, 2013, 05:17 PM   #3
Join Date: July 25, 2008
Posts: 45

Right on - 25 tick marks. Now if I can just figure out what it fits. It is well made and better looking that the photo.
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