Proofing a barrel

A correct proof charge will not make a safe barrel unsafe. Of course you should not just pack it with powder without knowing your goal (e.g. 30% higher gas pressure than normal). For muzzle loaders there are proofing tables available.

 

[mbritt]

Without having a chiropractic doctor friend who will let you carry your gun into his office for an x-ray; where does a person go to get such an inspection? I'm thinking next year I would like to build a howdah pistol using a piece of old damascus shotgun barrel and I will want to do a proof test and then inspection.

 

[Zonie]

I mentioned X-Ray because it is sometimes used to evaluate internal conditions of parts. Particularly those made from non magnetic materials like Titanium.
"Eddy Current" inspection can also be used but with both of these, we are talking about processes the average builder wouldn't have access to.

IMO, for steel parts, the best method is Magnetic Particle Inspection because it can determine the presence of cracks which are below the surface. If a crack exists, a magnetic flux will form at the edges of the crack. This flux will cause the inspection fluids particles to gather at the site and fluorese under black light at the site of the flaw. This will occure even if the flaw does not reach the surface of the part.

Fluorescent Penetrant or Dye Penetrant inspections are surface inspections only. If the flaw does not extend to the surface, fluorescent penetrant fluid or the dye will not find it.

There are several options when it comes to getting Fluorescent Penetrant, Dye Penetrant or Magnetic Partical inspections done.

The places which specialize in rebuilding automotive engines usually have Mag Particle inspection equipment and most of them will be more than happy to inspect your barrel and breech plug for a few dollars. Typically, their equipemnt is large enough to handle crankshafts and engine blocks.

Many gunsmiths will have some sort of Penetrant dye and will be happy to do the job for a few dollars. Not all gunsmiths have this so it is best to call ahead.
There are places which sell this, for instance
[url] http://www.vobaker.com/ndt/spotkit.htm[/url]

There are a number of "Inspection Labs" in large citys which will run either Penetrant or Magnetic particle inspections, but many of these places will charge an arm and a leg to do the job.
Another place to look is Tool and Die Shops and Small Machine shops who do work for large industries.

Here again, for the average hobby builder, buying this stuff is IMO going to the extreme when there are places that can do the job for you.

The importance of doing one of these tests cannot (IMO) be overemphasized if you've subjected your barrel assembly to Proofing but here are a few thoughts you ought to be aware of.

Magnetic Particle inspection, as I said, can find sub surface flaws. If it is done correctly, it can even find material flaws which exist naturally in wrought steel (nonmetallic inclusions they are called). For our purposes, these are harmless but it is good to know if they exist before the test so they are not missinterpreted as being caused by the Proofing.

Fluorescent Penetrant or Dye Penetrant inspection fluid will flow into any minute crack on the surface so a small scratch will appear to be a crack. Here again, it's good to know if these exist before the Proofing.
From this, you can see that IMO, it is a good idea to run the NDT before and after the Proof Test is conducted. :hmm:

Zonie

 

[musketman]

Fluorescent Penetrant or Dye Penetrant inspection fluid will flow into any minute crack on the surface so a small scratch will appear to be a crack. Here again, it's good to know if these exist before the Proofing.
From this, you can see that IMO, it is a good idea to run the NDT before and after the Proof Test is conducted. :hmm:

Zonie

We used to do this in the Air Force with jet engine turbine blades, it is a fairly simple process...

Make a weak solution of a water based fluorescent paint, saturate the area to be inspected with the mixture... (thinner and turpentine if using an oil based fluorescent paint)
Make it real weak, almost tranluscent, just need a hint of color...

With a damp rag, wipe off the excess then use rubbing alcohol to clean the part thoroughly...

Take the part into a dark room and with your hippy Uncle's black light, inspect it for cracks, the fluorescent paint will still be embedded in the crack and will illuminate once the UV light is turned on, providing you are not color blind and using a color you can't see... :hmm: :grin:

 

[Henry]

"Proofing would offer a gun maker legal security, because if a proofed gun fails later on after the customer screwed it up then he is out of the woods."


I have this discussion every now and then with my french friends . Centuries ago , it was one of the best ideas of the time , There is a report of a shipment of guns to Canada around 1740
where 53% of guns did not survive proofing

Today it is a good income for the governement
and a way to control gun makers ( who are
still in a restricted corporation to this day )

All the kits from Track of the Wolf , delivered
in France should be proofed by the proof lab
( at cost to the owner ) many people " forget " to do it .

There are also a few stories of spanish made
pistol with nice proof stamps on them , bursting
in a competition .

My angle on common sense would be to test
a gun with the biggest NORMALLY USED LOAD ,
no more than that.

 

[TN.Frank]

From the Early Rustic Arms web site, Larry says:
"OUR STANDARD SMOOTHBORE BARRELS Standard lengths are 24" 36" 42" and 46" available in .50 .54 .62 and .75 caliber Cloverleaf groups at thirty yards are common. They are made up from industrial grade hydraulic tubing. It's 1026 mild carbon steel much stronger than anything made in the 18th century. I have proof tested them with 250 grs. of FFFg black powder and six patched round balls. I took caliper measurements of the diameter in six locations before and after with absolutely no change. Colerain brand octagon to round smoothbore barrels are available for additional."

That's Hydraulic Tubing, I'd bet a "real" Colerain barrel would do even better. No reason to risk it though, the factory probably already proofed it or at least a few from that batch that your barrel was made out of. I'd just use a reasonable load and shoot it and have fun.

 

[Capt. Jas.]

Frank, I read that as Larry has tried it on "A" tubing barrel and not that he proofs ALL tubing barrels that go out of his shop. Is this correct?

 

[TN.Frank]

That's what I got too but still, it goes to show just how strong these barrels are so I wouldn't really worry about the Colerain barrel that he has. I'm sure it'll be fine.

 

[DMURPHY317]

I don't think you have much to worry about even if you fire off a double powder double ball load.

I recently did some proof testing of a cheap spanish barrel in an atempt to "blow it up". I just wanted to see how much it would take. I took measurments before, between shots and after and found no changes in the dimentions of the barrel. The loads stepped from max to 300% of recomended max load for both powder and bullet. No physical changes were noted in the measurements or "feel" of the bore when swabbing.

I would like to find a place to do the magnetic particle test as a confirmation of the barrel though. Anyone know of a place near Albuquerque that could do it?

Thanks for any help given.

 

[TFoley]

I would like to find a place to do the magnetic particle test as a confirmation of the barrel though. Anyone know of a place near Albuquerque that could do it? Thanks for any help given.

Try these people - Non-Destructive Testing, 5620 Modesto Ave NE. They do ALL kinds of non-destructive tests on any materaial you can think of - including tubes of any kind...suit ya?

Look 'em up in Yellow Pages.

tac in Tokyo

 

[DMURPHY317]

Thanks.