Wondering ?????

[John Taddeo]

Watching Guns international I noticed a new listing for a Parker 16 Gauge that had occurred some damage... not to get specific (look at the listing) could someone please tell me what 16 gauge load (factory or reload pressure) would cause damage such as this.. I would just really like to know where this forum would draw the line with load pressure with the ability to do what is pictured.. I am asking this assuming barrel wall thickness is sufficient... I don't want to discuss that particular gun ,just the pressure that would cause that damage..

[John Taddeo]

To be more specific... How much pressure would it take to do this to a good measuring everyday Damascus barreled Parker 16 gauge GH ?? With NO barrel obstruction...

[Angel Cruz]

I'm glad it was not me...

http://www.gunsinternational.com/guns-for-sale-online/shotguns/parker-shotguns/parker-gh-16-gauge-ruined-you-know-you-are-and-so-do-i-southern-sxs-2016.cfm?gun_id=100736629

[Rick Losey]

maybe more pressure than you are likely to fit in the shell

i would bet there was some debris in there


maybe - unless the seller knows and trusts the shooter - it would be a good practice to set a condition - yes - you can shoot it- here are two boxes of RSTs - $20 please - refundable if you buy it

[Brian Dudley]

Maybe a reload with more powder than should have been in there.

I want to know... Why pay the money to list an ad on GI just to publically shame an unknown, to us, party?

[John Taddeo]

Give me a pressure number that would raise your eyebrow in a 16

[allan.mclane]

Too-long, high-speed paper shells?

[Larry Stauch]

I'm more puzzled by Allen's avatar.

I doubt the person even knew they did it.

[allan.mclane]

I'm more puzzled by Allen's avatar.

My JRT with a chipper down the hole...

[John Taddeo]

Educate me.... does the location of the bulge say anything to what may have happened ??

[Patrick Lien]

Educate me.... does the location of the bulge say anything to what may have happened ??

maybe hot shells?
maybe long shells?
maybe long hot shells?
maybe thin barrels?
maybe any of these combinations?
maybe something else?

PML

[Paul Ehlers]

I saw the listing this morning & got to pondering all sorts of questions about it myself.

Because I'm not an expert, I don't have the gun in hand to inspect & I wasn't there to see the deed done. I have to believe the poster of what his take is on the matter.

I just hope this doesn't grow a life of it's own and feed the Damascus blow-up myth's & legend's of using nitro powder. IMO: There is just too many possible variables in play here to truly speculate on what the cause may have been.

[Scott Janowski]

My guess is a base wad on a previous shell caused a partial blockage.

[Jerry Harlow]

I doubt the person even knew they did it.


I also doubt they knew as it is subtle compared to this photo. The Damascus pattern makes it less visible. I would guess factory heavy 2 3/4 inch loads with standard 12k psi pressure in 2 1/2 inch chambers.

Here is a set of 12 GA VH barrels I purchased from Brian Dudley in this condition. I'm guessing on these factory 3 inch shells in the 2 3/4 inch chambers, as the bulge is four and a quarter inches out. Now whoever did this you would think had to notice the first one and you wonder why they did it again? Maybe the excitement of a gobbler in front of them?

p.s. I don't think the GH is worthless now. It still has some value although a fraction of the before value.

[Jerry Harlow]

My guess is a base wad on a previous shell caused a partial blockage.

Possible for once but not twice. You may have not noticed he is showing both are bulged.

[greg conomos]

Well...I guess the old saying 'Never lend someone your car or your girl....' applies here. In fact, you could use 'hot load' instead of 'rod' and it would work for guns, too.

[CraigThompson]

Maybe a reload with more powder than should have been in there.

I want to know... Why pay the money to list an ad on GI just to publically shame an unknown, to us, party?

Depends what level he's at on GI . Generally a bigger dealer gets the higher priced deal and you can list all you want for one price . So if that's the case this listing cost him nothing .

[Russ Jackson]

I saw it yesterday ,what a shame and although I have never met Steve in person,the first 28 Ga. Parker I ever purchased was from him and he was a Pleasure to deal with and a Fine Gentleman , I think he is, as he said in the ad ,Boiling , maybe just beside himself and hoping the shooter will at least own up to it if they in fact knew about the damage ! At the least an apology would surely be in order ! Just my opinion , I haven't called to inquire of the gun or spoke with any one about it !

[Richard Flanders]

I think this is heavy load damage, not obstruction. Both bbls being bulged indicates that, and they look equally bulged. Just my guess. Nice gun; what a shame. I'd have a go at taking the bulges out were it mine and would feed it nothing but low pressure loads after that, but you'd be wailing on them pretty good to take them out in that location. It would be an interesting project to at least give it a try.

Thanks to Edgar for the post below. Sounds like taking the bulges out is not an option. A real shame.

[edgarspencer]

I saw this gun at Hausmann's and both bulges are right at the forcing cones. Additionally, they go all the way around the diameter, right into both top and bottom ribs, which, to me, says the barrels would have to be taken completely apart to tap the bulges down. I am also of the opinion that they were 2 3/4" hot shells.

[Rich Anderson]

I saw the gun as well and doubt this set of barrels is salvageable. Another member here had a similar experience with a 16ga hammer gun. I don't know if he ever got the barrels repaired.

IMHO the obvious and least costly approach is to look for another set of barrels and would think fluid steel ones would be easier to come by vs Damascus.

[Phillip Carr]

I would be curious if anyone has seen the results of shotgun barrels that have failed proof testing. It would seem to me the opertunity to budge a barrel during the proofing is elevated. The data of guns tested would provide us with results in a controlled situation of what might happen to shotguns fired with proofing shells. My understanding is that these shells are loaded to about double the normal charge. I realize dents, wall thickness, and other variables would effect the results, but still there should be patterns of barrel bulges.

[Dean Romig]

Rich, that was me, as you know, and Brad repaired my barrels and I shoot it all the time now. He told me that if it was anything but Laminated Steel he wouldn't even have attempted it. Something about Lam that makes it more resilient than the other composites...
I wrote about the gun in Parker Pages less than a year ago - "Shot to Destruction" is the article to look for.

I'll bet a dollar that a set of fluid steel barrels of that vintage would have suffered similarly (or blown out) under the same circumstances.





.

[Eric Eis]

I saw this gun before, and it was a great gun, and no the bores were clean. One of these two people shot this gun and returned it to Steve, and if you have ever dealt with Steve he will always say "go out and shoot it", bring it back set it back on the table. Say yes or no it didn't fit or whatever and he will say fine (I have seen him do it many, many times).
I cannot believe that the person that did this, did not have enough backbone and/or been man enough to say I'm sorry I screwed up your gun what can I do? If I know Steve he probably would have cut him some slack and said that happens and worked something out, but no, the guy just dropped it on the table and went on his merry way:cuss:. I know Steve has been steaming about this for a few months, the person that did this has no excuse :nono:

[edgarspencer]

I would be curious if anyone has seen the results of shotgun barrels that have failed proof testing. It would seem to me the opertunity to budge a barrel during the proofing is elevated. The data of guns tested would provide us with results in a controlled situation of what might happen to shotguns fired with proofing shells. My understanding is that these shells are loaded to about double the normal charge. I realize dents, wall thickness, and other variables would effect the results, but still there should be patterns of barrel bulges.

Phil, In proof testing, they use a shell of the proper length for the chamber.
I think the type of hull has something to do with what happened to Steve's gun. Many, but not all, plastic hulls are skived, and this tapered wall section of the crimp portion may blend with the forcing cones so that the wad doesn't meet with a strong resistance. I don't have to worry about what the chamber length is when I decide to shoot a particular gun that doesn't get much use, because I only load, and only buy 2 1/2" shells.
I think quality Damascus barrels, in good condition can easily tolerate higher than our normal pressures, but maybe not so well when a shell too long for the chamber, is thrown into the mix.

[Dean Romig]

It would be interesting to know ALL of the circumstances involved.






.

[John Taddeo]

Just for the sake of asking anyone's non-committed and honest opinion... What would you guess would be the necessary generated pressure (without obstruction) in those barrels to cause them to bulge..
How about a ballpark ???? And would an off the shelf modern factory load generate that pressure ?? I am not trying to nail anything down here I am just trying to get educated on what is really the case here.. I have read of people shooting 2 3/4 hulls and Wal-Mart specials and I am now hearing the extra length may be an issue at the forcing cone.. I will only shoot 2 1/2 hulls because I just don't know and as such stay on the safe side, what say you ??

[Eric Eis]

John good question, I don't think even a Promo load could cause that, maybe as was said before a base wad came off and then the gun was fired again.

[John Taddeo]

Allow me to start this off... Would anyone think 15,000 PSI chamber pressure would cause a normal set of 16 bore Damascus barrels to bulge in this manner ?? I would like to get an opinion on a number to get an idea of a how much of a buffer zone I have between my low pressure loads and what would cause a potential situation.. I am not looking for the hairy edge zone....

[Paul Ehlers]

I don't believe you would find any factory loads that would approach 15,000 psi. A crazy reload maybe. Possibly one with a double charge? Could 20,000 psi do it? I don't know.

My question is if this shooter bulged these barrels due to hot loads. What condition are the other guns in he was shooting that day? Surely he didn't just have these two hot loads with him. This was at the southern SxS shoot so his loads would have probably been shot in other similar guns as well.

The other question I have is about how common is it to have base wads come loose and cause obstructions? I've been around a lot of guns and shooting & can honestly say I've never seen or experienced it. What are the odds of having two base wads come loose in two different barrels on the same gun & bulge both barrels at approximately the same place in each of them?

Personally I think there's more to this story. I want to believe Steve, it's his gun and he was the one that experienced it in real time. I'm thinking that it's a mystery that will never be solved without more concise information.

[Dean Romig]

There's a LOT more to this story that we will probably never know. I don't think we can learn anything from this exercise.





.

[Bruce Day]

The current SAAMI maximum pressure for a 16ga 2 3/4" cartridge is 11,500psi regardless of shot and powder loading. At 80 percent of proof pressure, this requires minimum SAAMI compliant proof of 15,365 psi for a 16 ga gun, manufacturers may exceed the minimum standard .

Current production cartridges may be at or below the 11,500 pressure, particularly 1 1/8 loads.

At the time the Parker in question was made, the normal max pressure for 16 cartridge was 10,200 if I recall correctly, this gives a minimum proof load of 12,700 that the gun would have been tested with.

Tests have shown that chambers 1/4 " short increase pressure over nominal 2 3/4 by about 5 percent. Therefore assuming it was short by 1/4 " ( which may or may not be true) , a possible pressure could have been 11,500 plus 575, 12,075.

Therefore, the maximum pressure that factory shells loaded to maximum SAAMI specifications would have provided exceeds the load pressures the gun was intended for but remains less than what the gun was proofed with. The few tests done and reported in DGJ have demonstrated that the tested composite steel barreled guns withstood at least 4000 to 5000 psi above proof before they experienced non elastic deformation.

Neither the bore ID nor wall thickness has been disclosed for the gun in question. That information is critical to any informed analysis. O framed 16's , which this may or may not be , often do not have much wall thickness to spare.

[Bruce Day]

We saw a fairly new Italian over under rupture forward of the chambers at the Southern about ten years ago. He was using Winchester trap handicap gold loads that would have been loaded to SAAMI max.

I have an acquaintance who had a Guerini rupture halfway down with factory handicap loads. He saw the shot cup fly out on the previous shot so it was not a squib and stuck wad issue. He later had the barrels measured, bore ID was standard but the wall thickness was less than .020, how far less I don't recall but they were made surprisingly thin.

[greg conomos]

It's possible that the offender didn't even know the barrels had swelled. I could easily see myself shooting a gun at an event where there were lots of people and commotion and never paying that much attention to the gun. Keep in mind the swells are just that - gentle swells - and not ruptures or jagged edged. The Damascus pattern helps hide them, too.


I'm not taking sides....but I gotta say whenever I let someone shoot one of my guns I am very specific about what shells they use. Very specific.

It appeals to the ego to be a laid-back gun dealer who jauntily hands someone a multi-thousand dollar, 100 year old gun while casually saying "Bring it back when you're done..." But I think the dealer in this case has learned a lesson the hard way and will be less magnanimous from here on out.

"Don't lend someone your car or your girl...someone might throw a rod in 'em."

[Dean Romig]

I'm not taking sides....but I gotta say whenever I let someone shoot one of my guns I am very specific about what shells they use. Very specific.



Whenever I let someone shoot one of mine, not only will I insist on what shells they will use - I will hand them a box or two of MY shells.





.

[edgarspencer]

I'm not taking sides....but I gotta say whenever I let someone shoot one of my guns I am very specific about what shells they use. Very specific.

It appeals to the ego to be a laid-back gun dealer who jauntily hands someone a multi-thousand dollar, 100 year old gun while casually saying "Bring it back when you're done..." But I think the dealer in this case has learned a lesson the hard way and will be less magnanimous from here on out.

Couldn't agree more

[Bruce Day]

All the commonly available factory loaded 1 oz 16ga cartridges I am aware of generate chamber pressures below 10,200, or the design max working load for the gun. 1 1/8 loads are over that to the full current limit of 11,500. It seems implausible that a person would come to shoot targets with 1 1/8 oz 16 ga loads.

We have yet to be told the bore or wall thickness of the bulged barrel gun.

At the time this G grade 16 Parker was made, the Parker recommended load was 7/8oz at 2 1/2 drams. How do you know the shooter did not go to the RST tent 75 yards away and get a box of shells with exactly that load? Why would that not be the most likely scenario?

[Brian Dudley]

Whenever I let someone shoot one of mine, not only will I insist on what shells they will use - I will hand them a box or two of MY shells.

Very true. That way if something goes wrong, you have no one to blame but yourself. At least you know what shells are being used and if you reloaded them, then you know who may have made the mistake.

[Rich Anderson]

How do you know the shooter did not go to the RST tent 75 yards away and get a box of shells with exactly that load? Why would that not be the most likely scenario?

I highly doubt someone bought a box of RST just to shoot a gun a couple of times. More likely they had 16ga ammo and used that. It's not out of the realm that someone used 1 1/8th loads for shooting targets either.

I believe this gun is a #1 frame.

[Drew Hause]

http://pic20.picturetrail.com:80/VOL1373/6511424/24532497/412718116.jpg

"I don't think we can learn anything from this exercise."

Few more insightful words have been typed :)

HOWEVER, having participated in a number of barrel bulge/burst and shotgun blow-up discussions I'll babble anyway ;)
I believe a 2 part barrel burst failure analysis and metallurgical study will appear in the DGJ Fall issue.
Lots of information, and scary pictures here, along with some anonymous sniping :(
http://www.shotgunworld.com/bbs/viewtopic.php?f=5&t=366087

1. A Parker Service and Proof Load table was published in the 1930s and reproduced in The Parker Story p. 515. 12g 2 3/4” shell Service Pressure is 10,500 psi. Definitive proof used 7.53 Drams (no doubt) black powder and 2 oz. shot with a pressure of 15,900 psi. The pressure was (likely) measured using LUP and modern transducer values would be 10-14% higher, or more than 17,500 psi. I am not aware of any definitive information as to turn-of-the-century Parker proof pressures.

2. Under the 1896 British Rules of Proof, 12g 2 1/2” and 2 5/8” chambers (bore .710-.740) maximum service load was of 3 1/4 Dram Eq. with 1 1/4 oz. shot.
https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA296&dq
Definitive Proof – 6 1/2 Drams Proof-House Black Powder with 1 2/3 oz. No. 6 shot = 10,100 psi + 10 - 14%
Supplementary Nitro Proof with 4 1/2 Drams of C&H No. 2 T.S. powder and 1 2/3 oz. shot = 16,400 psi + 10-14%

3. 16 bore British Service charge was 1 oz. 2 3/4 Dram Eq. = 38 gr. Bulk Nitro powder. Published pressures + 10-14%:
C&H No. 4 - 7,480; “Schultze” - 8,250 psi; “E.C.” - 8,960 psi
The U.S. 16g standard was 1 oz. with 2 1/2 Dr. Eq.; likely about 7500 psi with Bulk Powder by modern transducers

4. There are a number of bursting pressure formula; Burrard used the Alger Burst Formula:
Burst pressure = Ultimate tensile strength x 3(OD – ID) / OD + 2xID

There is also Lame, Boardman & Lame, American Standard, and Barlow's:
P=2 S t / D
P=Bursting pressure in psi.
S=Tensile strength of material in tube wall.
t=Wall thickness in inches.
D=Outside diameter in inches.

Barlow’s refers to a pipe capped at both ends with a static pressure (a pressure cylinder). Shotgun barrels are not designed to be pressure vessels as one end is open and the pressure rises and falls quickly. I've discussed this issue with a mechanical and a metallurgical engineer, and there is essentially NO formula that can be used for shotgun barrels. Nor can the Hoop Stress Formula be reliably applied.

NOTE: every formula requires knowledge of the tensile strength of the metal AND the wall thickness. Without that information any speculation is at best a guess.

Wallace H. Coxe, in "Smokeless Shotgun Powders: Their Development, Composition and Ballistic Characteristics" published by E.I. du Pont de Nemours & Co. in 1931 cites a study in which a fluid steel barrel was cut to 9” and capped, then a series of progressively increasing pressure loads fired. The barrel cap was blown off and barrel burst at 5,600 psi.

4. From Major Sir Gerald Burrard, The Modern Shotgun, "Volume 3, The Gun and The Cartridge", 1948:
“In the case of an obstructional burst the really essential evidence is the ring bulge. If there is a ring bulge, there must have been an obstruction…”
Odd to have obstructional bulges at the same place in both barrels, and Burrard also makes the point that "rib lifting" almost always occurs with ring bulges. which I do not see.

5. A study by the Royal Military College of Science, sponsored by the Birmingham Proof House and the British Association for Shooting and Conservation, showed that an obstruction by 2 fibre wads (total weight of 4 grams) was sufficient to bulge or burst a 12 gauge barrel shooting a 28 gram (slightly less than 1 ounce) load. Peak pressure occurred 22mm (.866”) past the leading edge of the obstruction.

6. This is a 1902 16g No. 0 L.C. Smith with chambers extended to 2 7/8" with wall thickness at the end of the chamber of .096". Likely the victim of 16g "short magnum" shells with 1 1/4 oz shot

http://pic20.picturetrail.com:80/VOL1373/6511424/24519472/408859003.jpg

Radiography thereof

http://pic20.picturetrail.com:80/VOL1373/6511424/24519472/408857932.jpg

7. So what happened to these barrels?
My opinion, which is of no greater validity than anyone else's, is that this was NOT obstruction but inadequate wall thickness from previous honing.
"Mirror bores" in any vintage double should be huge red flags.

8. It might be relevant that some "low pressure" loads use powders with a slower burn rate, producing a lower peak pressure BUT slightly MORE pressure further down the barrel. Note the DuPont Oval curve below

http://pic20.picturetrail.com:80/VOL1373/6511424/24488932/410772139.jpg

Red Dot vs. PB (no longer available)

http://pic20.picturetrail.com:80/VOL1373/6511424/24488932/406243470.jpg

[Bruce Day]

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.

[Paul Harm]

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.

[Joe Wood]

+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?

[greg conomos]

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.

[Rich Anderson]

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.

[Mike Koneski]

Whenever I let someone shoot one of mine, not only will I insist on what shells they will use - I will hand them a box or two of MY shells.





.

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

[Jeff Higgins]

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

[Daryl Corona]

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.

[Craig Budgeon]

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.

[Paul Ehlers]

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 !

[Drew Hause]

Craig: Austria is a member of The Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives
http://www.cip-bobp.org/homologation/en/tdcc_public?page=1&cartridge_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.

[Rich Anderson]

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.

[Drew Hause]

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?

[Hal Sheets]

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.

[Rick Losey]

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

[greg conomos]

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.

[Bill Murphy]

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.

[Rich Anderson]

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

[Drew Hause]

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/VOL1373/6511424/24513874/410515292.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.

[edgarspencer]

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

[greg conomos]

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

[John Taddeo]

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

[Dean Romig]

The variation left vs. right?

[Drew Hause]

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/VOL1373/6511424/24488932/411834258.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/showthread.php?p=158096#post158096

http://parkerguns.org/forums/showthread.php?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

[John Taddeo]

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

[John Taddeo]

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

[Drew Hause]

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

All pressure - distance curves

http://pic20.picturetrail.com:80/VOL1373/6511424/24488932/410772139.jpg

http://pic20.picturetrail.com:80/VOL1373/6511424/24488932/314583132.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/VOL1373/6511424/24488932/412289224.jpg

[Dean Romig]

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

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.





.

[edgarspencer]

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

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.

[Bill Murphy]

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

[Larry Stauch]

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.

[Drew Hause]

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/1F2sQuPm05IE4VWYYnCkvuXmYEzQoWd_SQgaAfUOZEFU/preview

[John Taddeo]

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 ??

[John Taddeo]

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

[Drew Hause]

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.

[edgarspencer]

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

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

[Drew Hause]

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

[Daniel G Rainey]

An honest man would have owned up to it !

[Jim DiSpagno]

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