Proofing advantages.

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Col4570

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Hi just joined THR,thought I would show you something that could have caused me some discomfort to say the least.I have been making guns for many years and have never had a mishap .this was just another Flintlock Gun I sent the Barrel 003-10.jpg for proofing here in the UK.
The material was obviously wrong for the application.
 
I sent the Barrel to the Birmingham Gunbarrel Proof House routinely .The test obviously showed up the fact that the material I used was of the wrong grade.My first failure since I have been submitting barrels since 1975.A lesson well learned.
Regards all.
 
Birmingham England,We have the London Gunbarrel Proof House and the Birmingham Gunbarrel Proof house.
 
002-17.jpg
This is the gun when finished prior to Proofing the barrel.This winter I will make another barrel to higher specifications.
 
Nice looking flint shotgun. Do you build as a hobby or do you sale your finished products?
 
Just as a hobby now,at one time I used to do some work for money but now being of advanced years I make my own stuff.
 
Yes,I must confess that I was annoyed but the alternative could have been a disaster.I had shot the Gun a few times with light loads,2.5 Drams black Powder and 1oz of shot and she was quite responsive and came up good.On reflection and in the light of World events,a minor problem and a project for the winter.
 
That is interesting (and unusual)...

blackpowder barrels made of modern steels seldom fail so totally in proof firing.
Do you know of what material the barrel was made (did you make it yourself?)
Was the material heattreated and tempered, and, if so, to what specification?
It is always possible that there was a flaw in the steel to begin with: as a barrel maker, I have seen barrel-spec barstock, both chrome-moly and stainless, with seams and/or pipes running the fill length of the bar. Sometimes these conditions are not detected before the barrel is completely finished internally, and, when found, there is no remedy except to discard the flawed barrel blank, though the steel supplier may sometimes make the defective material good.
PRD1 - mhb - Mike
 
Yes I agree it is unusual for a Black Powder Barrel to blow so badly.At the breach the thickness is .250" at the Flats and slightly more to the peaks of the Octagon.I usualy have made B P Barrels of mild steel that have stood the massive proofing Charges.In this case although the Steel machined and filed easily I think it is brittle,according to the cristalised edges at the Burst.The Steel was a piece of what I thought was High Pressure Solid Drawn Tube.If you can see that a strip has split from the barrel.A crack extends all the way to the muzzle through the sight hole.Thanks for your advice on this critical subject.
On close inspection I can see a dark patch at one point in the Split,this could be the starting point of the burst.
 
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Good thing it blew during proofing! Probably saved someone's eyesight and your hands.
 
I believe...

you may have mis-stated the thickness of the barrel walls at the breech:
.250" seems (and looks, in your photo) more likely.
High-pressure solid-drawn tube of the wall thickness you apparently used should be strong enough for a muzzle-loading barrel - but isn't intended for such use. This type of tubing is intended for high static pressures, but not for the shock incident to peak pressures in firearms - it may be too hard for best tensile and yield strengths.
If you acquire your tubing from a steel supplier, he should be able to furnish you with the chemistry and physicals of the particular tubing, and, if I were going to use such tubing for barrel making, I'd be certain that the specifications were within the proper range for that use.
It is also possible that there was an inclusion in the material, forming a 'stress riser' which caused the failure at that point in proof firing.
If you are unsure about the actual nature of the material... the lesson is in the result.
I do want to compliment you on your workmanship, though.

PRD1 - mhb - Mike
 
Hi, Col4570,

Is "PROOF REJECT" an example of British understatement? It seems just a bit obvious.

I am sure you have made more of those guns than I have, since I have never made any, but it seems to me that steel tubing is not a good material for a barrel, even for black powder. Making "seamless" or drawn tubing can draw an occlusion out for a considerable distance, leading to what amounts to a long flaw in the resulting barrel. That may have been what happened here. Welded tubing does not have that problem, but it has a welded seam that can also conceal a flaw in the barrel. For that reason, tubing is not usually recommended for the high pressures found in firearms, even black powder firearms. AFAIK, quality barrel makers start with bar stock and drill the hole, rather than trying to use tubing. More expensive, but the barrels are much less likely to have flaws.

Jim
 
I'm curious about the Spanish barrels that blew up.Does anyone have more information on them?Thank you.
 
Yes .250".The Tubing had been in my workshop for many years and had a polished internal surface.On reflection I anticipated that it was of the same Specifications as the previous barrels I have made.As always I use the Proof Houses to test my work and in this case it proved to be worth the exercise.
I have straightened out the Under Rib which had twisted and curved,The Breach Plug with its stainless steel Touch Hole Cone has survived and the Barrel Wedge is OK. P1010015-1.jpg
 
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