after proof load bbl. measurement ?.

[ron w]

just curious,....have you ever mic'd  across the flats of a barrel at the chamber, before and after a good stout proof load and found a difference in measurement ?.  how would you consider a barrel that showed an increase is ATF measurement after the proof load ?.

[Pukka Bundook]

Ron,
The question may be academic, but if a barrel Did show an increase, it would be no good.
I say this because if it did it once, (show a larger reading) it could do it again I'd think.
Must also add that for a barrel to stretch like that, it would have to be awfully soft, and pure iron barrels worked very well without any stretching.

[Mike Brooks]

For my own personal guns I don't proof at all. If it has a barrel made by one of the leading barrel makers I just load it up with what I consider a   normal charge and shoot it. If I'm not in heaven after the gun goes off all is well and I carry on working up a load.. Of course I live closer to the edge than most of you.

A lot of guys worry a lot more about this sort of thing than I do.

[Daryl]

Not sure if this pertains to steel, but damascus welded barrels in the Jolly-Old England were allowed to be hammered back on bulges after final proof, 3 times, seems to me. If it withstood the 4th proof load, it was deemed passed proof and thus stamped.
This was noted in Greener's book and may have been for smoothbore barrels only, I don't remember the particulars.

[Daryl]

I've never proofed one - on purpose, but did proof my .69 accidentally, but only with a single ball, and 330gr. of 2F.
I have also fired it with a powder charge (82gr.) and ball and powder charge (82gr.) and ball. That kicked pretty good as well & the GRRW barrel
withstood it all.  But then, it was only 82gr. 2F with 1,046gr. of "ejecta".
I don't do that any more.

[David R. Pennington]

I used a new old stock barrel from 1973 that I wanted to proof for my own piece of mind. I measured the barrel at 1” intervals and recorded each measurement. I double charged and double balled and fired it with a fuse 3-4 times then remeasured and found no change.

[ron w]

not looking for any fault or cause thereof,.....just wondering (academically, as suggested) if anyone ever did it.  I realize that if a barrel is capable of withstanding the charge,...it shouldn't expand. if it expanded,..it has essentially failed the proof load .

[Darkhorse]

I never proof test any of mine. However, I too have accidently proof tested one. It was in the mid 70's and I was just starting out with a TC Renegade in .54 caliber and I was deer hunting from an elevated stand. A nice buck chased 2 does right in front of my stand where they all stopped. I shot at the buck with my normal load of 120 grs. of 2fg and hit a vine. Amazingly none of the deer ran so I slowly stood up. About that time the does walked and the buck followed so I got in a hurry. Instead of measuring my charge I just dumped a bunch of powder down the barrel. Stupid and inexperienced I know. When I seated the prb it would only go halfway down the barrel. The buck was gone so I didn't shoot.
So when I got home I lay the rifle on a blanket and tied a rope to the trigger and put several sandbags behind the butt. I got behind the front tire on my  truck parked just behind the rifle and pulled the rope. The recoil knocked aside the sandbags, slid the rifle across the ground and bumped the front tire.
No obvious damage was done to the rifle but I measured across the flats with a micrometer, each measure an inch apart, the entire length of the barrel. There was no swelling of any kind and no other sign of damage to the barrel.
It was a stupid thing to do but I learned several things from this episode and have never come close to repeating it.

[Hungry Horse]

I helped an old friend build a trade gun with hand made furniture, a second hand lock, and a surplus 27” 1880 vintage  20guage shotgun barrel from Dixie Gun Works. He took it to Idaho and kill an elk with it. But the second day he went grouse hunting and got into trouble. After a shot, and a miss, he reloaded in the snowy landscape, and the ramrod must has compressed some air, and pushed the wad, and shot up off the charge. He fired at a grouse and was nearly knocked off his feet by the recoil. He brought the gun home, and asked me to disassemble it and check it for unseen damage. Taking it apart was a challenge, because all the pins, and cross bolts were bent. I pulled the home made  breech plug, and carefully measured the barrel inside and out, and compared it to an unfired barrel from the same source. It was fine, not even a slight bulge. We reproofed it, and reassembled the gun, with new pins and crossbolts.
 By the way, this gun has an upward tang bolt, that is quite common on earlier trade guns. It was the only fastener that showed no damage.

Hungry Horse

[jerrywh]

 In the first place, I only proof barrels that I made or altered a lot in cross section.
 Then I mark the barrel at every 6" for the total length. After proofing I remeasure the barrel at each mark for expansion.  Remember the barrel was cold when you took the first measurement so to be accurate it must be cold when you take the last one and each one thereafter. And take the measurement across the same flat each time. 

[Daryl]

not looking for any fault or cause thereof,.....just wondering (academically, as suggested) if anyone ever did it.  I realize that if a barrel is capable of withstanding the charge,...it shouldn't expand. if it expanded,..it has essentially failed the proof load .

Depends on the proof laws, I'd say.
However, if you received one of those that needed hammering-in on a bulge, that did pass the second, or third proof load, it would be stamped as passing proof and you would never know - most likely.

[Dphariss]

not looking for any fault or cause thereof,.....just wondering (academically, as suggested) if anyone ever did it.  I realize that if a barrel is capable of withstanding the charge,...it shouldn't expand. if it expanded,..it has essentially failed the proof load .

Depends on the proof laws, I'd say.
However, if you received one of those that needed hammering-in on a bulge, that did pass the second, or third proof load, it would be stamped as passing proof and you would never know - most likely.

I think the hammering back down probably work hardened the steel and it eventually passed. Work hardening is what gives leaded screw stock it high number. But its also not great for gun barrel applications.  But the British damascus was very good barrel steel, the best quality is fully capable of use with smokeless and they still use it in England for shotguns if you have enough money. Though I don't think the stuff made for cheap export guns was as good (from reading W Greener's the "The Gun" from the 1830s) but the British proof was pretty rigorous so it had to pass proof and some foreign guns would not pass according to W.W. Greener.  I tend to proof everything. Though I have one with a 4150 GB quality barrel I have never proved and a GM pistol barrel I have not proved. But the rifle does not worry me much, its 4150 and 1 1/4 across the flats. If I sell something its proved according to my 1896 W.W. Greener's "The Gun and It's Development" tables or even heavier. I just don't have the special proof powder. But Swiss is pretty fast.

Dan

[Pukka Bundook]

Dan,

You are very much on the money regarding work hardening of bulged barrels when hammered back and re-proofed.

In fact you are on the money with all your post.   

When a mate and myself  back in Blighty made a 4-bore barrel, we tested according to Proof House rules,  (27 drams and 4 Oz shot,  Provisional proof)   then the definitive proof, but forget the charge for that now.

Seemed like a sensible thing to do with a big bore like that.   

Cheers,
Richard.

[E.vonAschwege]

If the barrel changes in dimension at all after proof then I would call it no good.  The proof we used at the CW shop was a charge the same weight as the bullet, done twice.  The French sometimes proved with a normal charge and double bullet.  One barrel I welded up had no difference in external dimension after proving, however it did open a tiny hairline silica inclusion about halfway up the tube (and this was a 6.5lb barrel!).  You had to use a magnifying glass to see it - only evidence there was an issue was that it leaked water afterwards... a 100 hour paperweight. 

I love that bit about hammering a shotgun barrel back down if it bulged - not something anyone today would be willing to bet their livelihood or life on, though it's done for dents in shotguns all the time. 

Frankly, I've seen lots of American made barrels from the colonial period that I can't believe survived their hard use, given the grain tears, burn checks, and inclusions.  Obviously I'm not going to put powder in an antique, but I'd be willing to bet some of them would "harmlessly" burp gas out the side. 
-Eric

[Daryl]

Dan,

You are very much on the money regarding work hardening of bulged barrels when hammered back and re-proofed.

In fact you are on the money with all your post.   

When a mate and myself  back in Blighty made a 4-bore barrel, we tested according to Proof House rules,  (27 drams and 4 Oz shot,  Provisional proof)   then the definitive proof, but forget the charge for that now.

Seemed like a sensible thing to do with a big bore like that.   

Cheers,
Richard.

Dan and Richard, W.W. Greener mentions the work hardening from hammering in the bulges in "The Gun and It's Development" 9th edition. I neglected to mention it.
Seems to me, Purdey was making Damascus barrels into 1929 or so.

[Pukka Bundook]

Daryl,

Yes, Greener covers this in his book.  Mine is also the 1910 edition. 
 
I have one old barrel from about 1690-1700, and it is full of cracks and all kinds of terrifying problems, Yet, it had passed London Proof!
I did try it myself (remote) and it held allright, as I was going to stock it up.   The barrel is marked to Thomas Bannister.   As it came from the Eastern US, I wondered if it was from one of the Hudson Bay arms he supplied.   It's 53" long if I remember right.
I Had wondered if Hudson bay accepted less perfect barrels, but still, it was stamped by the proof house.

All the best,
R.

[Jerry V Lape]

As I understand the proof testing done by  European Proof Houses the barrels are measured to increments of 10 thousandths of an inch or the equivalent in metric measure.  And any change is a failure because it indicates the elastic limits of the barrel material was exceeded.  Clearly barrels expand under pressure of the combustion but if that expansion is within the ability of the barrel to recover the elastic limit was not violated.  If any permanent expansion is noted it is assumed that subsequent firings will accumulate further expansions leading ultimately to failure.  I don't believe crude measurements following extreme loads is an effective experiment telling us anything other than the barrel didn't blow up on that particular shot if there is a cumulative effect on the elastic limit of the steel once it has been exceeded.  Fatigue failure of metal is something familiar to all of us.  It takes a lot more effort to start the bending the first time and less each time thereafter.   

[JCKelly]

If American-made modern steel barrels have a crack in the steel they might shatter from a heavy load but are unlikely to bulge.

As far as waking up in Heaven, I might be more concerned about waking up in hospital with diminished basic mathematical abilities.