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.

[J.B. Books]

John, if I were you I would do as your doing, describe the gun as completely and honestly as you have. If you believe the gun to be in original condition (no evidence or suspicion of honing or reaming) state that too. The gun is going to sell itself, it's unique and it's gorgeous. I am sure you are disappointed, but better to know now up front than have a buyer come back to you later with a potential issue to try to get some money back. I think you are in stronger position for knowing up front.

[Drew Hause]

Sherman Bell's pressure test published in The Double Gun Journal Summer 2002, "Finding Out for Myself, Part VI, Smokeless vs Black", p.19 and summarized in Volume 17: Issue 4, Winter 2006, p. 39

1 1/4 oz. 3 3/4 dram GOEX FFFg Black Powder at 1240 fps and equivalent load Blue Dot
...........................1 inch.................. 6 inches...............12 inches
BP.......................5900 psi...............4100....................2100
Blue Dot...............6000....................4300.... ...............2300

1 1/2 oz. at 1236 fps Blue Dot (weight not stated)
...........................10,000................. 4,400...................2000

[Bill Murphy]

I'm a little surprised about the 10,000 figure, but 1 1/2 ounces is not a friendly load in a 12 gauge at that velocity anyhow.

[Kevin McCormack]

Jay; Jay; Jay!!! -

Your absolutely excellent post looks like a court stenographer's transcription of the wonderful conversation that you, John Hosford and I had at the NE SxS in June! John's gauge paid for itself at about 15X MSRP in the first year I owned it. When dealers see you coming with it, they know whether to give you a little table space to set it up and measure or head for the Porta Potty across the parking lot in double time.

[Steve McCarty]

LOL: I know you guys are purists and love machines that measure things like barrel thickness. That's fine of course.

My method is simplier. I have several old shotguns...maybe half a dozen. I inspect dozens monthly. My method is to peer down the bore and then run my finger down the outside of the tubes. If the bore looks okay and I don't detect any bumps or ripples along the outside then I inspect the muzzles. If they don't look "spooky" thin, and the gun "talks to me", I'll make an offer.

What constitutes "spooky". Well, you've got me, but like pornorgraphy, I know it when I see it.