Lots of previous discussions regarding wall thickness measurements; here's Bill's protocol
http://parkerguns.org/forums/showthr...?t=7889&page=5
1. My gauge has a 5/16" hole in the "block", so I installed an eye bolt in the hole with the eye facing out.
2. I tied a generous loop of clothesline rope to the eye bolt with loops and knots to make holding on easier.
3. You need an assistant if measuring at a gun show or auction. The assistant needs no skill or strength.
4. The assistant will hold the barrels steady on a table with a cushion and the end to be measured over the edge. An assistant is to be preferred over a vise or weights, especially at a show or auction. No weight is heavy enough to hold the barrels steady.
5. The micrometer is zeroed with the rope holding one end horizontally and the ball supported at the other end by the fingers.
6. With the micrometer properly zeroed, the ball end is inserted into the barrel, run from the open end of the barrel to the extent of the rod and the results recorded. The rod must not contact the interior barrel wall for accurate results.
7. The assistant will rotate the barrels on the pad 90 degrees and the results recorded as in the previous instructions.
8. Another 90 degree rotation will complete the measurement of that end of that barrel. The fourth quadrant cannot be measured.
9. Do the same to the other barrel.
10. Reverse the direction of the barrels and do the same from the other end. This should result in 12 recorded minimum thickness measurements from one set of barrels.
Youtube on how to use the Hosford gage. Part one and two.
http://www.youtube.com/watch?v=1jQZn4kohH4
http://www.doublegunshop.com/forums/...=313266&page=1
I use bungies to affix the barrel in the (weighted with 25# of shot) box in which I carry everything. The barrel is plenty stable, horizontal, and easy to rotate. The owner of the barrel sits to my right (good ear
) recording the numbers as a call them out.
If I might make a plea, to each of us and esp. dealers, a single MWT number is really not much help without documenting
where that MWT was measured.
And of little meaning without documenting (muzzle) end of chamber, forcing cone, and at least 9" and 12" numbers.
I've witnessed a dealer running a gauge quickly down (one side of) a barrel, and then pronouncing the barrels "fine" based on the MWT.
OK. Rant over
