Barrel Wall Thickness Readings

[edgarspencer]

Call it a Clymer, Manson, or Brownell, the gauge is the same. Two things are certain: It's a perfectly reliable tool in the hands of someone who knows how to use it, and, There are a lot of people who don't use it correctly.
I like John Hosford new gauge better than the original version. The 'beam' is either an aluminum investment casting, or CNC machined. The old one(original version, with 1" aluminum tube) is just as good.
When I hear people complain about the perceived lack of rigidity of the rods on a Manson gauge, I am almost certain their technique is lacking.

The barrel must be Horizontal! Whether you're fixing the lugs in a soft jaw vice, or someone is holding them on a table edge makes little difference (unless the table is on a thick rug, the backyard, the beach, or some other soft footing.
Hosford's barrel support rod is the best part of his gauge kit (he will sell them separately) as it allows you to easily rotate the barrel to get readings all around.
Hosford's YouTube video on Zeroing, and using his gauge is very good, and the points he makes are equally true if you're using a Manson (Brownell, Clymer, etc) gauge.
The diameter of the rod inserted into the barrel is the same with all gauges, and has to be small enough to get freely into the bore. My Manson gauge came with a 1/2" rod, and 9/16" ball, so it was too big to measure 28 gauge guns. I simply made a new rod, 7/16", with 1/2" ball.
The eyebolt I added to my gauge, like the ring on the Hosford, makes holding both easy, and repeatable.
The other (lower) rod simply holds the dial indicator, and since the dial is on the bottom side, gravity means it flexes to it's same amount each time.
As long as you're paying attention, and don't allow the upper rod (Same true with Hosford) touch the barrel, you'll get steady, and repeatable readings every time.
Initially, I thought Tony's vertical measuring fixture was the cats meow, but quickly realized it's actually easier to influence the rod deflection, and even fussier to get true, and repeatable results.
I've watch lots of people struggling with zeroing the dial on their indicator. Best way (Take it from someone who has a terrible hand tremor) is to hold the gauge between the ring and EXACTLY AT THE BALL, visually observe it's either at zero, or note the reading, Then hold your thumb on the end of the indicator rod, which prevents the dial from deflection, and rotate to zero.
Because of my tremor, When checking ZERO, I suspend the unit between two points, one at the ball, one at the ring.

Note to that Nit Picking fuss budget (Yeah, You know who you are) who spends more time looking at stuff in the background of my pictures, Bite Me! The Maid is on vacation.

[Craig Larter]

Edgar: Thanks for an explanation I could understand. Got it to work with no issues. I had almost given up on the gauge. Craig

[Dean Romig]

Thanks Edgar - I'll have to take private lessons.

The "maid" told me she refuses to go in there....





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[Garth Gustafson]

Nice tip. Now go clean up your room.

[Bill Murphy]

Thank you, Edgar. I have explained the correct use of the Manson gauge many times, but it gets lost in the translation. For just over $100, it is the best gauge on the market for the price. You can't take Tony's gauge into a gun show without a "bearer", so it is useless unless you are at home.

[Drew Hause]

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

[edgarspencer]

My interpretation of MWT is the Minimum I find, after measuring up, down, and sideways. Meaning, the number I give someone on a gun I might describe, is the thinnest wall thickness I find, Anywhere. Otherwise, it's WT, and not MWT

[Drew Hause]

I measured a honed Smith barrel that was .018" from 14-16". I think the 14-16" part is worth sharing. End of chamber was fine at .106". 9" from breech also inadequate at .032". 9" from muzzle .022".

Measured another honed chain damascus Smith 4E that was .032" 9" from the breech. A dealer reporting that as the MWT without the location would be...uh...worrisome.

[Dean Romig]

Drew, is your "14"-16" measured from the breech or the muzzle?





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[Drew Hause]

Sorry Dean. From the breech.