Minimum Wall Thickness at Point of Proof

[edgarspencer]

I get the shakes each time I recall an 'over-restored' gun which measured .013" just at the end or the fore end. Several PGCA members were looking over my shoulder when I measured it. We had just walked across the parking lot at a certain venue in Southern New England.

[OH Osthaus]

Yes

When we talk minimum wall thickness we tend to concentrate on the what of the measurement, when the where it occurs is a critical factor

[Dean Romig]

The more critical section of the barrel is the first 10" - 12" from the breech. Forward of that area pressures have dropped off radically and barrel wall thickness, though important, is far less critical. Though I would not shoot a gun with wall thickness of .013" I wouldn't hesitate to shoot a gun with less than the currently "approved" .025" - say, down to as thin as .020" or even .018" or .019" IF the chokes are Mod or less and more importantly, IF they are not pitted and IF they have never been honed and IF they have not been refinished in any way - in other words, IF they left the factory EXACTLY as they are today. (Extremely difficult to determine in a gun that has been heavily used)
Some guns were made as light upland guns and as such, the barrels were struck to what the factory considered to be safe to shoot with factory specified loads.

.... but that's just me - not suggesting anyone else do the same.





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[Drew Hause]

Lots of information here
https://docs.google.com/document/d/1...vwLYc-kGA/edit

and http://parkerguns.org/pages/faq/BarrelThickness.htm
NOTE: the image on the FAQ is NOT wall thickness recommendations; it is the dimensions used for the barrels evaluated by the Birmingham Proof House Trial. There was no chamber cut.
Scroll down a bit here
https://docs.google.com/document/d/1...EK8OtPYVA/edit

I would observe that doublegun dealers now commonly run a wall thickness gauge down one side of a barrel and pronounce the barrel as "fine with a MWT of .030". As said, that number alone is meaningless and if a dealer, or the smith evaluating the barrels, can't provide the minimal wall thickness after measuring top, bottom and side (because of eccentricity) of the end of the chamber, the forcing cone, every inch to 9" from breech, and 9" from the muzzle, and MWT and where, a second opinion is mandatory.

BTW: I will have a table near the Parker tables at the Vegas show, and will have my bore gauge and wall thickness gauge to provide barrel evaluations, for a fee to offset the $375 table cost. I'll post a reminder as we get closer to the show, and I'm looking forward to meeting more of my "imaginary internet friends" in person

[Drew Hause]

Cross posted from another thread

How to use the Hosford gauge

Part 1
https://www.youtube.com/watch?v=1jQZn4kohH4

Part 2
https://www.youtube.com/watch?v=sfBP7a0TbjM


Henry gauge. The short metal piece is .038" to confirm the gauge.





The barrels are secured to a weighted box with bungie cords



I affixed a tape measure so the rule is not needed

[Jon Hancock]

That's a pretty neat tool. Sorry gentlemen, didn't realize so many have posted on this thread. You all have been most helpful.

[Craig Larter]

I use the Galazan wall thickness gauge. I find it easy to use. It would be interesting to compare wall measurements on a set of barrels using the Hosford gauge and the Galazan gauge.