Thanks Drew Your hypothesis of causation is the same as mine. Any load from RST, Remington, Winchester, Federal, Fiocci or Rio that could have been placed in the gun would certainly have been less than original proof pressures and likely less than max working pressure.

Honing sure does produce high condition beautiful barrels. Before anybody blames the shooter, the gun needs to be inspected.

With normal wall thickness, the chambers blow with too high a pressure. The barrels past the chambers blow if there's a obstruction. With both barrels bulged in the same place I wouldn't think it's an obstruction, but thin barrels. I fully agree with Bruce and Drew.

+3 for thin walls and most likely lengthened cones. I can't imagine a factory original one frame 16 not having enough meat to digest almost anything. And to happen in both barrels in the same place makes it almost a certainty in my mind.

Steve Barnett is one of the "good guys".

PS: I shoot a lot of damascus guns and consider all to be perfectly safe. However, a few months ago I got stuck with a GH 12 with 28" barrels that upon measuring the walls near the chambers am convinced they would be very dangerous to shoot even low pressure loads. I mean they are scary. Fortunately I have a set of widowed barrels that fit almost perfectly and are off to the smith for final fitting. I hate to destroy the original barrels so am trying to figure out how to mark, plug, or whatever the bad ones so they will never be fired. Any ideas?

The honed barrel theory is a good one...but it's still just a theory until we get some more complete data.

To counter, I'd offer that Steve Barnett would know they were thin and would not have had the gun out for open shoot day.

I doubt we will get any additional data. I don't know if Steve checked the wall thickness prior to purchasing or trading for the gun. IF he knew it was thin the gun would have NEVER been on the table.

Dean, how many of your guns can I borrow?? :rotf:

Joe could those barrels be lined or perhaps shot with sub-gauge inserts?

Honing or lengthened chambers would be the likely cause at that location. I once owned a GHE 12 which developed a bulge in the chamber when I was using a set of chambermates in 28ga. The "o" ring on the insert failed and the pressure was essentially trapped within the chamber. I found out later that the previous owner had lengthened the chambers to 2.75". That was a long time ago, way before I knew anything about barrel modifications.

To answer the question you asked. Minimum proof pressures in Austria for 16 ga. and above is 12,800PSI, for smaller gauges the minimum is 14233PSI. Proof loads manufactured by Remington produce pressures which exceed standard loads by as much as 50% and are clear plastic and marked as proof loads. Remember this when you remove a bulge from a barrel the bulge has already yielded once and removing the bulge forces the metal to yield again. Finally since I value my eyes above all my other senses I test Damascus guns I want to shoot by tying with the top rib against an 80 lbs. truck tire, adding 30 ft. of string to each trigger, lying face down on the ground with a hard hat, and pulling both strings one after the other. Yes I used proof loads and hunted the gun there after.

After thinking about this some more. I've reminded myself of a personal experience I had with a CE grade Fox with 30" cromox fluid steel barrels.

I bought this gun when I was fairly new to older doubles and was still in the make the gun the way I want it to be phase. I didn't like the full & fuller chokes it came out of Philly with, so I sent it out to a well known double gunsmith to have them opened. I stressed that I didn't want them opened if the wall thickness didn't allow the procedure to be done. He supposedly measured them & we agreed to have him do the deed. When I got the gun back I took it out on a hunting trip in eastern Colorado. I forget the exact load I was shooting but they were a typical 6 shot pheasant load. "not one of these high power pheasant loads available today. A bird got up and I missed on the first shot, so I followed up with the second barrel.

My buddy that was with me immediately asked what I was shooting because it sounded funny. I started looking the gun over & found that both barrels had bulged at the lead to the choke tapers. Yes both barrels were bulged in the exact same spot shooting the same ammo! These shots were the first shells fired in the gun after the chokes were opened. Yep it only took one shot per barrel to bulge them.

I sent the gun back to the gunsmith and he immediately took the position that I was shooting too hot a load for the gun and wouldn't stand by his work. When I got the barrels back I had them measured for wall thickness. What we found was the walls at the start of the choke tapers were down to .010" where the bulges started. I've always felt that if I hadn't had the chokes opened that nice set of Fox barrel would still be bringing game to the table today.

I know it's a long story, but one I feel relevant to the theory of lengthened chambers. Live & learn !

Craig: Austria is a member of The Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives
http://www.cip-bobp.org/homologation...idge_type_id=7
12g 65mm and 70mm “standard proof” lead or steel (limited to no larger than 3.25 mm and max. fps 1,300).
Numbers are transducer BAR converted to PSI.
SERVICE pressure 740 BAR = 10,733 psi;
Maximum statistical individual pressure 850 BAR = 12,328 psi
PROOF 930 BAR = 13,489 psi

12g 76 mm = 3” LEAD “High performance/superior proof” transducer pressure
Service 1050 BAR = 15,229 psi
Maximum statistical individual pressure 1200 BAR = 17,405 psi
Magnum proof 1320 BAR = 19,145 psi

Both 65 and 70 mm 16g standard is SERVICE 780 BAR or 11,313 psi;
Maximum SERVICE 900 BAR or 13,053 psi;
PROOF 980 BAR or 14,214 psi.

Both 65 and 70 mm 20g standard is SERVICE 830 BAR or 12,038 psi;
Maximum SERVICE 950 BAR or 13,779 psi;
PROOF 1040 BAR or 15,084 psi.

I spoke to Steve last night and the barrels and chambers were to the original specs regarding wall thickness and chamber length. These barrels were not honed in any way. The bulge is approximately at 2 3/4 inches and the chambers are 2 1/2. This probably occurred by using a high pressure 2 3/4 inch shell in a gun chambered for 2 1/2 inch shells.

As a note of possible interest a friend of mine was shooting his Fox Sterlingworth when the barrel burst at the chamber. The previous shot went off without any problems and the target was broken. Sometimes things just break.

Thank you Rich. Could you please inquire as to what the wall thickness at the end of the chambers, at the forcing cones, and at the point of the bulges measures? That information is quite important to those of us who chose to use Pattern Welded barrels, and have followed this thread with great interest.

Does The Parker Pages have a Mechanical Specification Drawing with the "original specs" for wall thickness by gauge?

steel shot ?
 

Has anyone thought of the possibility of shells loaded (or re-loaded) with STEEL shot? Both barrels, with the same problem, at or about the same time? It's got to be a load/barrel relationship issue. Not an obstruction.

In that case -I believe the ring bulge would be at the chokes. Not the forcing cone

Well.....I guess that settles the question of who the guilty party is once and for all. If I were in his shoes, I wouldn't go around advertising what I had done....or at least I would accept responsibility for it.

Drew has a good request, but there is some stretching when a barrel bulges or ruptures and you have to be careful where you take your measurements.

I'll try to get the measurements requested. Steve is in Montana currently.

Thanks again Rich. Please also confirm the chamber length and bore measurements just proximal to the bulges.

The issue is not to dispute Steve's statement, nor to assign blame, but to reach some conclusion as to the cause of the barrel failure.

It is my sincere hope that this will not end as most posts regarding barrel/gun failures, at least on doublegunBBS and trapshooters.com, have ended; with no definitive, or at least learned, explanation. Modern guns sent to the maker for a failure analysis and metallurgical study disappear, and when litigation is involved, details of any settlement are made confidential.

Something like this would be definitive

http://pic20.picturetrail.com:80/VOL.../410515292.jpg

To be clear, I have found no Specification Diagram for wall thickness from any turn-of-the-century U.S. maker. That information would be invaluable to those of us measuring wall thickness and providing an opinion regarding originality, and safety.

This got my curiosity up, so I measured a set of 0 frame barrels from a 16ga. DH
I was surprised at that variation.

2 or 3 thousandths of an inch is pretty tiny.....

.016 .... not that tiny...

The variation left vs. right?

Thank you Edgar. It appears the pin is measuring the forcing cone wall thickness? Could you please post the end of the chamber measurements?

It has been my experience that the thickness at the forcing cone frequently exceeds that of the end of the chamber. The angle of the forcing cone is more acute than the external taper of the barrel; as illustrated

http://pic20.picturetrail.com:80/VOL.../411834258.jpg

This may not apply to small gauge and continental game guns, and does NOT apply to guns with chambers lengthened.

And so we all don't have to go looking. End of the chamber measurements.

http://parkerguns.org/forums/showthr...096#post158096

http://parkerguns.org/forums/showthr...?t=1565&page=4

English:
James Purdey (1898) 12b., 2.5" chambers: ≥ 0.100.
James Woodward (1909) 12b., 2.5" chambers: ≥ 0.098
James Woodward (1909) 12b., 2.5" chambers: ≥ 0.103
Boss (1897-8) 12b., 2.5" chambers: ≥ 0.090
Westley Richards 12b., 2.5" chambers: ≥ 0.090
James MacNaughton (1895) 12b., 2.5" chambers: ≥ 0.095
Wm. Pape (1898) 12b., 2.75" chambers: ≥ 0.100
EM Reilly (1887-1904) 12b., 2.5" chambers: ≥ 0.091
Henri Egg (1870) 12b., 2.5" chambers: ≥ 0.108
WH Monks (1875-87) 12b., 2.5" chambers: ≥ 0.116
WC Scott (1905-6) 16b., 2.75" chambers: ≥ 0.105
Francotte (1938) 12b., 2 5/8" chambers: ≥ 0.098
Westley Richards (1905) 20b., 2.5" chambers: ≥ 0.098
WW Greener (1922) 20b., 2.75" chambers: ≥ 0.098

Belgian:
Francotte (1894-5) 12b., 2.5" chambers: ≥ 0.085
Francotte (1896) 12b., 2.5" chambers: ≥ 0.085
Francotte (1930) 20b., 2.5" chambers: ≥ 0.095

French:
Verney Carron (1950s) 12b., 2 5/8" chambers: ≥ 0.100

German:
Wilhelm Brenneke (1902) 12b., 2.5" chambers: ≥ 0.110

Would it be safe to say the weakest point in the illustration is the beginning of the forcing cone ???

And by legnthening the chamber you would change the angle of the forcing cone..

A better question is what is the safe wall thickness where the pressure peaks?

All pressure - distance curves

http://pic20.picturetrail.com:80/VOL.../410772139.jpg

http://pic20.picturetrail.com:80/VOL.../314583132.jpg

1 1/8 oz 1200 fps modern powders, recognizing that Unique is slightly modified "Infallible". Unique and Green Dot were equivalent.

http://pic20.picturetrail.com:80/VOL.../412289224.jpg

Yes and Yes to both questions and by lengthening the straight wall of the chamber deeper into the ever decreasing taper of the outside of the barrel you are negating the safe wall thickness of the barrel that the manufacturer had built into the gun when filing the barrels to the safe taper they were made with.





.

As Requested. I could get varying results are different points, but still at the same depth, however I took these at the same points as the previous two pictures. None were lower than these measurements.

What point are you making by showing those measurements? They seem pretty safe.

Wall thickness gauge
 

Looks like I'm getting one of those wall thickness gauges like Edgar has........

I have noticed the barrel walls on post smokeless powder era Damascus guns are way thicker than the ones made prior to that.

This has been really interesting and educational.

Larry: your cut-off would need to be about 1895. Most Live Bird and Inanimate Target competitors had switched to DuPont, “E.C.”, or “Schultze” Bulk Smokeless, or Ballistite Dense Smokeless by then.
Please see
https://docs.google.com/document/d/1...UOZEFU/preview

Gotta ask.... on the pressure graph illustration, is the peak pressure generated (as shown at 1 inch from the breach) from the end of the shell at the forcing cone or in the base of the hull ??

According to the chart pressure is at 4000 psi at the forcing cone... with over 100 thousandths wall thickneness

John: short version is that pressure was measured by lead crushers placed in holes bored in a special barrel every inch. Pressure is essentially in all directions. "Chamber Pressure" is usually the 1" from the breech.

The top chart is TONS/sq. inch and is for 1 1/4 oz 3 3/4 Dr. Eq. loads :eek:
Ballistite maximum pressure at 1” was 4.9 Long Tons = 15,344 psi
Schultze at 1 3/4” was 4.5 Long Tons = 14,000 psi
DuPont Bulk at 1 2/3” was 4.1 Long Tons = 12,656 psi
All three beyond today's SAAMI recommended max. pressure, and turn-of-the-century Live Bird competitors were using those loads in damascus barrel guns.

Better numbers from another pressure - distance graph
Ballistite Dense (1 1/8 oz. at 1232 fps = 3 Dram Equiv.)
Breech - 2.9 Tons per Square Inch (UK, Long) = 8624 psi
(Using Burrard's conversion formula: 2.9 x 1.5 = 4.35, 4.35 - .5 = 3.85 TSI, 3.85 x 2240 = 8624 psi)
2 1/2" - 2.2 Tons = 6272 psi
6” - 1.2 Tons = 3718 psi
12” - .81 Tons = 1602 psi

3 Dr. Schultze Bulk 1 1/8 oz. at 1220
Breech - 1.69 Tons = 4558 psi
2 1/2” - 1.49 Tons = 3886 psi
6” - 1.36 Tons = 3450 psi
12” - .92 Tons = 1971 psi


Wallace H. Coxe, in “Smokeless Shotgun Powders: Their Development, Composition and Ballistic Characteristics” published by E.I. du Pont de Nemours & Co., 1927, “Measurement of Pressures”
The common method of taking pressures in small arms in this country is known as the Radial Pressure system. A housing is built around the barrel, and a hole drilled through the housing and barrel into the chamber at a distance of 1 inch from the breech and at right angles to the axis of the bore. The hole is then bushed and drilled to a uniform diameter of 0.2250 inch. Then a piston is made the length of the piston hole and 0.2250 inch in diameter. Next the piston hole is lapped to permit the piston to fit snugly without either sticking or getting out of alignment.
In firing the gauge, the piston is inserted and seated, then a lead crusher cylinder is placed on the head of the piston and held firmly in place by a screw and anvil attachment built into the housing. When the cartridge is fired, a portion of the same gas pressure that pushes the bullet through the barrel drives the piston against the lead cylinder and compresses it.
The length of the lead crusher cylinder after compression is naturally less than before the shot was fired and the difference between the original length and the length after compression therefore represents the amount of pressure which has acted upon the lead. Thee exact pressure is read from a table giving a pressure reading for every remaining length reading and commonly called a Tarage Table.
Pressures that are determined at ballistic laboratories are merely relative values and are not absolute values.


NOTE: The Tarage Table conversion may be for pressure expressed as Tons / Sq. Inch or Pounds/ Sq. Inch (PSI).

Rifle pressures were usually measured by copper crushers (CUP).

Pressure is now measured using piezoelectric transducers.

I'm not attempting to make any point, Bill. I posted them at Dr. Hause's request.

TTT in hopeful anticipation of follow-up, and relevant to Bruce's Chamber Pressure thread

An honest man would have owned up to it !

Someone with short arms, long pockets and a big deficit in the ethics department is cowering the dregs of embarrassment and will say I never sent or recited classified info on my emails