Barrel wall thickness

[OH Osthaus]

the Manson gauge

http://www.brownells.com/.aspx/pid=2...HICKNESS-GAUGE

there is a brace that is not shown in the picture that prevents twist

I have practised with it in several modes until I know I can get consistant measurements in different settings.

along with a Skeets bore gauge, a scale, a tape and a caliper (not in the pic) you have a compact set of tools that will give you some level of confidence when you consider a gun.

[Bill Murphy]

Jay, the gauge that Brownell sells for about $100 is the "Manson Gauge". Dave Manson worked with Clymer Reamers and went out on his own and built the gauge that bears his name. The "hanging from the ceiling" method of using the Manson gauge is now old tech and quite inconvenient compared to a method that I was taught by our friend Jon Hosford. Jon realizes that not everyone is a potential customer for his wonderful tool and generously shared this information with me. If there is interest, I will explain it on the forum again as I have in the past.

[Bill Murphy]

The Manson tool can be bought from Dave Manson directly if you choose. His website is mansonreamers.com. The shotgun reamers on the site are very nice items.

[double barrel]

Bill,
Please do. I have one of the $100.00 gauges and am not convinced I am getting accurate measurements.
Thanks,
Ken

[Bill Murphy]

OK, here goes, as Jon explained to me and as I have been using ever since.
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.
11. In my opinion, this procedure, though a bit complicated, is much more convenient and accurate than the old method of hanging the gauge vertically.