Barrel Wall Thickness Readings

[Drew Hause]

This is my barrel evaluation template. Nothing proprietary about it so feel free to use. The Word doc is more clear.



There is ample space at the bottom for comments ie. DO NOT USE THIS BARREL

[Bill Murphy]

Drew, thank you for repeating my instructions for the "best" method for use of the Manson gauge. It seems a bit wordy, but that was the best I could do. A you-tube video would simplify my instructions if I could ever get around to doing that.

[Bill Murphy]

With an assistant, I completed a search of bore measurements and wall thickness measurements of a pair of William Evans sidelock guns at an Alderfer's auction several years ago, using a Galazan bore micrometer and a Manson wall thickness gauge, in about twenty minutes. That included the transcribing of the measurements onto a legal pad. This allowed me to purchase a cased pair of second tier London sidelock guns in high condition for a price that anyone without these measurements wouldn't have had the nerve to purchase at any reasonable price. The guns were perfect, original, no work done on the guns including extending chambers, all bores completely untouched. My tools cost me about $225.00 and I have used them for decades.

[edgarspencer]

Originally Posted by Bill Murphy

A you-tube video would simplify my instructions if I could ever get around to doing that.

I couldn't help myself, but we've been waiting so long for you to post a picture, a video just seems too good to be true. But, If it did happen, I have no doubt it would get an Emmy I just love a good movie, and popcorn.

[classicioi]

Edgar,

Thanks for getting everyone trained up on taking measurements .... now hopefully we'll get to see some more readings ...

[Woodcock survey]

Mr Spencer and Mr. Hause, thank you both for your explanations. You have cleared up a subject which for me was very muddy.

[B. Dudley]

A manson gauge is very capable of getting accurate thickness measurements.
There is lacks is the limitation of bore size it can measure. As I recall, when I had mine it would not go into a tightly choked 20g. muzzle.
And the size of the ball on the end of the rod does
Not allow measuring into pitted areas as much as a hosford gauge does.
But, for the money, a Manson is a good piece of equipment.

The areas that Drew measures on his record sheet are the areas I like to sample As well. At the forcing cones, around the forend lug (about 9-10” out) and The minimums found out in the second half of the tubes.

[B. Dudley]

Another thought of mine...
The whole wall thickness subject can be a little mirky to
Some as to what is “safe to shoot” and what isn’t.

There are really two ways to look at it. Ultimately one can base their safety conclusions on thresholds of overseas proof house standards. But, anything beyond that is simply based on individual experiences and knowing “well, I have shot other guns with comparable measurements to ‘the subject’ gun, so it should be just fine.
In that type of scenario, different people may have different opinions on what is “thin”.
I have heard people say that they dont like anything with a minimum under .030”. Well, if that is the case, a TON of guns left factories then and now that were/are too “thin”.

[Garhart Stephenson]

Great discussion and explanations. Having just performed these measuring procedures, I am glad that it has been pointed out how to properly zero a gauge (which takes rod flex out of the equation of zeroing), the importance of horizontal zeroing/ gauge use to eliminate gravity's affect on "rod flex" that alters readings, and the importance of not allowing the rods to contact the barrel (or anything else) which would induce rod flex errors. Excellent descriptions!

[MD*GSP]

If someone wanted to make a really, really nice gage for measuring wall thickness, there are woven phenolic materials (rods) available that are super rigid and would possibly suffer little to no flex when used. Further, a notch could be cut on the end of the rod that would allow various screw-in indicator tips to be used instead of a ball on the end which would allow for very accurate measurements of pits or other irregularities in the bores.

A gage made like that would be a bit spendy, however as they say, the right tool for the job is priceless. Here's a picture of various tips that could be used on the end of the rod. I think tips like these are what Brian's referring to..