doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Wall Thickenss Guage

I'm in ther market to buy a barrel wall thickness gauge and came across these on ebay. A shotgun forum in the UK highly recommends them but what are your thoughts? Do the ultrasonic barrel wall thickness gauges work on our shotguns?
http://www.ebay.com/itm/GM100-Ultrasonic...igital-Testing/

i think its gone

this?

http://www.ebay.com/itm/USA-GM100-Ultras...=item3f3697ca71


i see in the specs its low range is 1.2MM about 50 thousands - so limited use for shotguns

Looks like the item has been removed from ebay.

I can't comment on the ebay item, but a mechanical engineer friend who is also investigating NDT of pattern welded barrels found that the $1900 TI-007 Precision ultrasonic wall thickness gauge has a measurable range from .006" to 1" with a resolution of .001". However the manual states that the minimum radius for convex surfaces measured is .5" or a little larger than a 4 bore, or 2.5" for a concave surface.

Yes, ultrasonic units are great, but even the tightest radial transducer needs an OD greater than our shotgun barrels... Sorry.

I've been doing some of my own research and here is what I know. First you would most probably require a dual transducer of over 5 megahertz....about twice the price of a single transducer. The radius of our shotgun barrels does present a problem with the ultrasonic wave dispersion however that can be somewhat overcome if using a microscopic probe. With a microscopic probe the surface needs to be smooth. Questions of pits on the inside and anything on the outside I.e. Etching on a Damascus barrel, rust, dents are just that questions. Until testing occurs the answer is unknown. There is a shotgun forum in the UK that has some experience and recommends them. Price of the one recommended by Dakota instruments $2000.

That's the idea but low quality and most likely would not work. See above comments.

If you go on Ebay and search for the GM100 ultrasonic you will find about 20 listed from $65 to $165 buy it now price.
The difference in price looks to be the type of box it come's in.
They are all made in China and ship directly from China or
Hong kong.
Me personally, I don't think I would have much confidence in this unit.
In the specs it lists:
When the given thickness over 20mm, the accuracy is �1%; when the given thickness less than 20mm, the accuracy is �5%

This is a low tech solution to a wall thickness gauge that a friend of mine and I built. It works well.
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Stallones, Nice gauge...but the coffee table it is sitting on is just as nice

There is a 3-pronged one in the forthcoming HOLT auction.
Have a look in their Internet catalogue.
Best regards
Felix Neuberger
(It is the type the old continent uses since long ..)

Which Holt? There are several on the internet..
Thanks
Ken

its www.holtsauctioneers.com .
Ask them for a condition report.
rgs felix

Bummer. It's in London.

Thanks
Ken

Brownell's Manson gauge, about $100. I have used this one for years.

I'm pretty sure that's the one I'm going to get. In previous threads some have raised accuracy issues, while other's have stressed it's a matter of proper procedure. Vertical vs. Horizontal use, etc. Got any tips?

Thanks
Ken

I have a question. If I use the Skeets bore gauge along with a dial caliper for measuring the outside of the barrel, subtract one from the other divide by 2, will this give you the dimensions needed? I realize it is giving you an average and will not allow you to pick up a thin part in one portion of the barrel but it should give you a good starting point or is my thinking flawed?

Don

Won't work. Barrels were struck off more on some sides than others, and the average isn't important at all. What IS important is the minimum wall thickness, and where it is on the barrel.

SRH

I have made and used the Manson style but I used it hanging from the ceiling joist. The trouble is you need two people, one is to write down your numbers or else you have to take it off the rod to do so. I also used chalk on the barrel to let me know where I left off. I got tired of that one and made the Galazan style. Mine will measure 10, 12 and 16 gauge on two rods. I cannot measure 12 gauge guns from the muzzle that have chokes less than .700.




Repeatable every time, I measure from top rib to bottom rib from 5" to 15" from breech then turn and put muzzle end in and measure from 17" to 23" I usually don't go farther as by now the wall thickness is increasing.

David
Neat!!

Next time you need to use it, set up your Camcorder and record your efforts
Then you can play it back and have the reading at hand

Mike

Mike, I don't have to worry about that now with this gage.

The Brownells works fine once you learn how 5o use it

Try using the three prong table mounted gauge at a gun show or auction, the places where immediate readings are necessary.

Have any of you used the Hosford gauge? It looks like a good tool to me, but I can't cough up $600 for it.

Nudge

John Hosford taught me how to use my Manson gauge in the horizontal position. He did that because he knew I didn't have $600 to spend on his gauge. What a guy. A great engineer and a great personality.

Here is one done to plans developed by a member here and built by another member, Wingshooter, although this one has been "prettified".

Not great for portability, but gets the job done. Like with them all, takes a little practice to get good, consistent results. Mike has built 3 or 4 now and just beautifully finished this one.

I'm sure I have posted this before right after I made it. Works very good and is a copy of the one that CSMC has. This is the one I built, two rods to measure 10-12 ga. and the other to measure 16 ga. The tape measure in-between lets me measure in increments of 2-4" or closer near the breech. I read from top of rib to bottom of rib at every interval, takes time, but I have plenty of that. There is a spring loaded lever on the one side and when compressed, is the same diameter of the rod .625 (5/8). On the opposite side is a 1/8" ball bearing and is set half the diameter of itself. This is my zero point that the indicator is set at. The spring loaded lever holds the barrel against the ball bearing. Readings are repeatable and within .001 of where I measured. The brass cone at the bottom with the thumb screw is how I hold it at the different increments and also centers the barrel on the cone.

I can read to 17" and then flip flop the barrel. I can only do this if the muzzle end is not under .690 for a 12 ga.

If I use my Starret indicator I can change the tip and read right down to the bottom of a top rib.

Pics not showing up for me, David.

I went back in on my end and they are there. Again this is from Photobucket and now unless you sign up and pay the pictures get deleted from other sites.
I will try and transfer them and post them from Imgur.

I downloaded the pictures of the wall thickness gage to Imgur.

I like the pretty one, almost as much as I like the Williamson example. However, my Manson will go to the auctions and gun shows. Very seldom do sellers come to my house to offer to sell me guns. The guns are "Out there", not in your gun room.