A Simple Proof Test Jig

[James Wilson Everett]

Guys,

Here is one I have used for many years, very simple to build, probably many of us use similar ones as this is not a new idea.  The jig is built with a stout board and two U-shaped staples, nuts on the back side of the board.  The breech is butted up against a wood cleat and held down by two simple wood wedges.  The wood cleat has a short life and needs to be replaced as needed.



The barrel is one that I made from an old wrought iron straight sided barrel, .32 caliber.  One of those gosh-awful nose heavy percussion barrels.  I reamed it out to about .42 and made it octagon to round, the same one shown in the barrel straightening tutorial.
With the barrel wedged in place and loaded with the proof charge, I make a big pile of powder covering the flash hole and use a double fuse.




I like to use two fuses because I have seen single fuses go out - now what do you do?  With two fuses burning you are sure of a bang.  Here is a photo showing the happy result, sometimes the wood cleat gets  bashed and needs to be replaced.



The last photo shows the staple - wedge - cleat construction - pretty simple.



Jim

[Don Getz]

Why??...........Don

[Robert Wolfe]

Don, if I made my own barrels from old wrought iron as Jim does I would want to proof them. Buying from a commercial barrel maker I don't see any need.

[David R. Pennington]

Jim, what kind of formula do you use to come up with your proof charge? Hopefully I will need to build one of these soon. We have a skelp welded up out of wagon tires that looks really good so far. Hopefully we can start welding it into a tube next session in the shop.
We had this discussion before about length. We started with 2 pieces of tire 36" long and welded them front to front to get a heavier piece. After welding we ended up with about 48". We still decided we needed more bulk so we welded another piece of tire to this skelp. Now it has grown to 60". Having not done this before, my next question is how much will it grow when we actually weld the tube? Do we have two barrels here maybe?
Obviously you have to breach the barrel before you proof but do you rifle it first or proof and then rifle?

[James Wilson Everett]

David & Guys,

Good questions.  

The barrel just tested above is fairly coarse wrought iron, I do not know if it is welded or drilled.  Since it is old and the bore was enlarged, I thought it prudent to proof it.  With such barrels and with the ones I forge, I use rather modest charges, just a bit over bore size in grains.  For the proof I double the service charge.  This test was at 90 grains FFg with a single patched ball.  I expect the service charge to be 40 - 50 grains.  

I proof test barrels after they are rifled, the barrel above is a smooth bore.  It is more difficult to rifle a barrel after the breech plug is installed as it is very difficult to start the cutter in the breech end over the thread & interior shoulder of the breeched end.  I have done this by machining a hollow "breech plug" at the exact bore size and included a tapered or funnel lead in to start the cutter.  Even with this, the cutter tended to grab at the unavoidable gap or groove between the "breech plug" end and the start of the bore surface.  My advice is to finish rifle, even to lapping, if necessary, before proof testing.  Of course, this makes installing the lock more fun as you have to "hit" the existing flash hole.

When I have forge welded barrels the skelp started at about 36", after forge welding it was about 44", and finished at about 42".  The thing really grows a lot in length, at least mine did.  My advise is to finish the weld,  then if more length is desired you forge it into the "swamped shape" to make it longer.  Try to avoid too much forging at the very ends of the tube as this tends to produce what I call "broomstraw splits" where the wrought iron will split along the slag streaks at the ends.

Jim

[Dphariss]

Don, if I made my own barrels from old wrought iron as Jim does I would want to proof them. Buying from a commercial barrel maker I don't see any need.

Pa Keeler thought the same thing, he stopped proofing because it was "pointless" they "never failed",  till a Douglas barrel split up from the breech about 8" at the first shot. He was a supplier and Douglas cut him off for putting the photos in Muzzle Blasts.
While ML makers have managed to hide behind the "handloader defense" so far its still better to proof.
If in doubt you might want to ask why all the modern makers use blue pills or just ask a lawyer or look at the lawsuit Remington went through over shotgun barrel failures.  These were modern steel too...
Besides if something like a vent liner is going to blow out its better for the maker to find it than the customer.

But that's just me.

Dan

[B.Habermehl]

Having had a cast patent breech fail on test fireing and subsequently ruining the gun, not to mention the dragon breath damage to my right hand. Yes I definitely will proof fire any barrel with a cast breech Assembly. However I don't proof separately if I am using a flint style breech set up using all machined parts. I do test fire any gun leaving my shop.

[Old Ford2]

To proof my barrels, I have several bolts with compatible threading to the breech plugs.
I have drilled holes through the bolts.
After each barrel is threaded for breech plug, a bolt with as mentioned through hole is installed into the barrel, assembled to a holding board.
Then loaded with a double charge of 3f, and three patched round balls.
At the back where the hole through the bolt is, a light priming charge of powder and a fuse is set in place.
This set up works well and is safe to use.
The barrels are attached similar as above ( A Simple Proof Test Jig )
Fred

[Dphariss]

The proof is not just of the barrel. The proof proves all parts exposed to firing pressure, the breeching and the vents/nipple seats. This needs to be done after all dovetails are in and any screw holes drilled and tapped. Its the last thing I do before test firing.

The materials used are subject to flaws and the work done is subject to human error.
It is irresponsible to send out an unproved barrel. We have to remember  that a failure can result in death or serious injury to a human being. As a result the barrel and all its attachments have to held to a much higher standard than a butter knife or a fork.

Dan

[James Wilson Everett]

Old Ford2,

I have an original and unused .50 cal double barrel that has Belgian proof marks, but no flash holes or nipple seats.  Apparently this was proof tested just as you describe by screwing in special proof testing breech bolts with some sort of ignition provision.  Thanks for the input.

Jim