Proof Load

[frogwalking]

I have a .46 caliber smoothbore barrel that bears Belgian proof marks from the 1890s.  It is, however, unused.  The iron from which the barrel is made is quite soft.  It is octagon in the rear, tapering to round toward the muzzle.  It is probably an idea of questionable merit, but I am making a gun out of it.  the barrel is inlet in the blank, but the hooked tang is not yet installed.  I think I will place the unshaped butt in a tire, as Turner Kirkland showed me in the '60s and fire it with a long piece of firecracker fuse stuck in the nipple.  I have in mind, 100 grains of 3 f powder and one patched ball.  I think this barrel came over in the 60s with the 12 tons of old gun parts Turner bought in Europe.  It is not my desire to blow it up, but to prove it safe for a sane load.  What think you?

[Daryl]

Standard method is double normal charge and 2 balls. The first bare, with no patch and the second patched.

[Hungry Horse]

 In all actuality a pistol barrel isn't long enough to let pressure build to the bursting point unless the charge is just stupid, or the ball isn't seated on the charge. It is likely that if the barrel is as soft as you say, it is wrought iron, not steel. I have used some of Turners warehouse finds in the past without any problems.

  Hungry Horse

[J Henry]

 Proof charging just show it didn't blow up that time,,you might have weakened it so next time it will..  But it's your head,,  but if your in doubt let the shooters on either side know so they can step off the  line or tell someone where you are going shooting and when you will be back...
   

[flinchrocket]

Frog, I think 90 grains would be a plenty,Imo. If it has a hooked breach why don't you just put the barrel in the tire and you will still have a stock!

[Steve-In]

I c-clamp mine to a 2x6.  I fire what I consider the load to be used, followed by 2x powder and 2 balls.  Kind of like what is shown in Gunsmith of Williamsburg. 
I guess it shows it did not burst THAT time but for me I never had one fail during or after.

[hammer]

If it has Belgian proof marks, even 1890, it has already been proofed to international standards.    Still valid so long as there have been no changes made to barrel or breech and there is no appreciable corrosion or wear.   Nothing wrong though with belt and braces to reassure yourself.

[Hungry Horse]

 Those barrels did come over in Turners boatload of Belgian gun parts. I have one as well. Mine is 30" long, and is OTR, about .47 cal. They were made for export "monkey guns" and were sold in Europe as garden guns. They make the best round ball shooting tradegun you have ever seen. A friend built a petite fuzzee for his young daughter, who just killed us with her round ball shooting. We got her on the shot firing part of the trade gun course though, but even then she did surprisingly well considering how small the bore was. They are a tough barrel in spite of the metal being soft by modern standards.

   Hungry Horse

[Jerry V Lape]

I would like to see the proof marks before getting too far along here but here is some information.  In 1890 a barrel alone meant for a shotgun would have been proofed in it's unfinished state as follows.  (Note the smallest Belgium bore size I have information about is .526).  The .526 would have been 1st proofed with 129 grains of fine black powder (probably similar to 3Fg).  and one 194 grain ball of bore size(no patch).  After final form was achieved second proof of 86grains and a 3d proof with the firearm fully finished of 43 grains.  Yours probably only has the 1st proof which would be a small stamp with oval containing an E above LG over a star.  Their intended service loawas probably the 43 grains.  In Britain the 1st proof would have been with 164grains and the last with 82grains over 2/3d oz of shot.  France would have been with 108grains and 463 grain slug.  1st Proof for German barrel of .526 in that same time frame would have been 123grains and 406 grains of shot.  Yours is a small bore yet so the proof loads would be even smaller.  I think some of the loads suggested by others here  are ill informed and far greater than necessary.  I will look further for smaller caliber smoothbore loads but I think the Europeans assumed smaller bores were rifled by the time yours was manufactured and proofed under a much different schedule.

PS:  Found a proof table for German muzzleloaders firing shot.  In 49gauge (.47 caliber) the proof load would be 81grains of a fine black powder used specifically for proofing, and 327grains of shot.  So again, well under the double ball double powder formula.  

Proof loading was more than a bursting test.  Barrels were carefully measured, before and after firing,especially in the area of the chamber and just forward of the load.  If the barrel changed dimensions after the test that demonstrated the barrels elastic working limit had been exceeded and it would not be passed.  Obviously a burst failed it too but most were rejected, even before firing, if the measurements were wrong.  The double load double powder test without sophisticated measurements is waste of time.  Modern shotguns are typically tested with approximately a 50% pressure above the maximum pressure for the commercial shells the gun is intended to shoot.  In 12ga that is about 18,000 psi and slightly higher as the bore gets smaller.  

[Mike Brooks]

I just load a gun and shoot it with a normal load if the barrel is sound. Of course I live pretty close to the edge.....

[Hungry Horse]

Mike, I heard you only get off the edge long enough to have it sharpened.

   Hungry Horse

[Mike Brooks]

Mike, I heard you only get off the edge long enough to have it sharpened.

   Hungry Horse

Good point.

 I blew up a muzzleloader once , no amount of proof loading would have prevented it happening.

[little joe]

A friend blew a 20 ga.  smoothbore up a couple yrs ago. The barrel split from the muzzle to within a couple inches of the breech. No known reason however the Lord was looking over him that day.  A VERY lucky man. I don,t know if proofing would have helped. It had been shot several hundred times.

[oldtravler61]

Always used the no more than double the caliber rule. An only one ball at a time. So far so good. Been fifty some years knock on wood (my head) .  Will stick with it. All metal stresses over time.

[Darrin McDonal]

The way Colonial Williamsburg proofs is 2 times the weight of the ball  powder with one patched ball. Can be repeated a second time. Eric Von  (Auschwege?) can chime in to verify this. Sorry Eric.

[Daryl]

The way Colonial Williamsburg proofs is 2 times the weight of the ball  powder with one patched ball. Can be repeated a second time. Eric Von  (Auschwege?) can chime in to verify this. Sorry Eric.

That sounds quite excessive to me. Even weight of ball seems high - a 20 bore ball will weigh 320gr. Double would be 640! yikes! Even a .45 ball weighing 128gr. x 2 is 256gr. in a .45!

Maybe I misread that post?

My 14 bore would be 960gr. of powder? Sounds more like a bomb to me.

[Joe S]

From Birmingham Proof House Tables

Scale for Proof of Small Arms of Every Description

14 Gauge - Proof Charge

Bullet for Proof                     1047.0 grains
Charge of Powder for First Proof    246 grains
Charge of Powder for Second Proof  164 grains

Service Charge

Powder Weight             82 grains
Ball Weight                     785grains

[Hungry Horse]

 When I built my trade gun about thirty years ago I used a 20 guage surplus barrel from Dixie. I proofed it the way they suggested in the back of the Dixie catalog, with a double charge, and a double ball. All went well except for the part where you stick the barrel in an old tire to fire the proof. That barrel went straight through the tire, and out into the orchard next to where I was living. I was lucky I found the barrel, and lucky my patching wasn't so tight that I got an air gap between the balls. I would now put a bare ball down on the powder, and a patched ball on top.

  Hungry Horse

[Daryl]

Standard method is double normal charge and 2 balls. The first bare, with no patch and the second patched.