doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com OT: Gun writing gone bad?

Chuck, and as a corollary, you own and shoot doubles with damascus barrels.

JC

Some here insist on something very wise Mr. Bell quotes:

"My mind is made up, don't confuse me with the facts".

JC

Chuck;
Not really a lot of info, have just seen a few photos & descriptions over the years of bbls with seams. I seem to recall someone posting one here on the board some time back. Burrard showed pics of several in his book & a few from other random sources. Fortunately between machining & proofing the majority never make it out the door, but a few have. These generally do not show up until after some years of use.
ItalianSxS;
The mat'l factor of most importance to a bbl maker is Tensile Strength. This is normally stated as a two part factor, namely Yield & Ultimate. Any time force is applied the mat'l will be stretched to some extent. The Yield point is where the elastic limit is exceded & upon release of the force the mat'l does not return to it's original configuration. Ultimate is of course the point at which it seperates/breaks/bursts etc. The higher the yield point in relation to the ultimate the less likely one is to have a bulge. The humourus part is that "Old Timers" eulogized their Damascus bbls saying they were more apt to "Bulge" while steel ones would burst. In either case a bulge simply shows too high a prerssure applied for the steel to properly resist. If this bulge occurs as a "Ring" bulge it is almost a given that a localized pressure spike was the cause, which was not the fault of the gun itself. "If" the pressure of the shell exceded the yield point of the steel, but not the ultimate then the entire bbl would have swollen. The pressure is of course in the form of a curve reaching it's max within the chamber itself & falling off quite rapidly to a more uniform pressure for the remainder of the bbl, gradually falling as it goes toward the muzzle. An "Overloaded" shell will thus burst the weakest point in the chamber.
Now consider this, say you load 1 1/8oz shot (12ga) ahead of a sufficient charge of BP to give it 1200 fps MV & it does so at a max pressure of 6K psi. We then load that same 1 1/8oz ahead of a smokeless charge & reach the same 1200 fps MV but at 10K psi. Now first we could say the smokeless load "Stressed the bbls more than the black", But Note, this was only in the chamber. As both loads pushed the same wt of shot with the same force the same amount of work was done. With a possibility of only an extremely small margin of error we could say the "Average Bbl Pressure" for both loads were the same. Since the chamber pressure for the smokeless was considerbly higher, we can thus conclude the presure spread out over the rest of the bbl was higher in the BP load. For a number of years after the introduction of smokeless powder the proof house used a supplementary proof for the "nitro" proof. Unfortunately as I have read on such things over a long period of time I do not now remember the source, but this was explained by the fact, that at that point in time the proofers did not have suitable powders to proof the entire bbl, without exceeding a desirable chamber pressure. The major portion of the bbl was proofed by the "Black Powder" proof with the chamber area being done by the "Nitro Proof". 99.98% of bursts forward of the chamber will be found to "Not" be caused by an overload or a defect of the gun itself. Those other few will be a major flaw in the bbl metal & can & "DO" occur in all types of guns, both old & new.
Not to be forgotten is the possibility of the shot charge itself becoming the obstruction from an improperly ignited load. This has been discussed here several times so will not go further into it unless someone has missed it & desires to. It is something to keep in mind though when loading to extremely low pressures with slow burning powders in particular.

Chuck H & 2-piper:

Some very interesting information presented by two guys who seem to know their stuff. I too worked for a metals company at one time:

2-piper:

Perhaps you could elaborate on this statement.

Quote:
"99.98% of bursts forward of the chamber will be found to "Not" be caused by an overload or a defect of the gun itself."

Jim

The most common cause of a barrel failure other than an improper load for that barrel is a barrel obstruction. Virtually all barrel bursts are barrel obstructions. This can be snow or dirt or insects, etc plugging or partially plugging a barrel. It can also be a "puff" load caused by oil in the powder, partially blocked powder column in the reloader, or any number of ways a reduced load or powder problem causes the wad, part of the shell case, or shot to stay in the barrel. It can also be caused by certain powder being very cold causing improper ignition.

Most hewre do know what a proof load is but there are some who may not. A proof load is a carefully calibrated load shot through each barrel after exactly measurements are made on each barrel. After the firing of the proof load, the measurements are made again. ANY increase in these measurements means that the barrel material has undergone a plastic deformation and this means the yield strength has been exceeded. The gun has failed proof test even if no overt damage has resulted. Now Joe out in his back yard putting an old shotgun in a tire and firing a very heavy reload in it accomplishes absolutely NOTHING. There may be plastic deformation that he does not see (meaning small or large damage to the barrel), or his load was not very hot after all and the gun may not be up to a full proof load. Don't try this at home.

Pete Hiatt, engineer

Jim, I don't own any Damascus guns, never have. So I have no dog in this fight . . . other than to question some of the long-held beliefs about Damascus strengths and weaknesses. I'm glad to have modern proof house testing on my side in this discussion.

If you haven't seen a blown steel barrel--not just bulged--I'd say you haven't looked much. Our "training aid" is fluid steel (I think an old Stevens, or Savage Fox B, but don't recall for sure) and it's peeled open right around the chamber area. We use it to demonstrate what might happen in case of an obstruction, like a 20ga shell dropped down a 12ga barrel--although I don't know that was the cause of failure in this case.

L. Brown
I haven't shot trap or skeet much for years (rotator cuff problem) so I'm not around a lot of heavy shotgun usage anymore. I did ask a couple of guys I know who are active shooters and they haven't seen any(burst barrels) either.
I HAVE seen some pistol failures lately as at least two Glocks have blown out in the chamber area at my gun club.
Here's a 9MM case from one of the failures:



Jim

I'm sure most Joes have enough sense not to be shoot'n guns with "plactic" barrels....

The "tire test" proves about as much as Sherman Bells test proved.

HomelessjOe, backyard engine'ere

A local target range near Cincinnati (called TARGETWORLD) had a S&W handgun that was used as a loaner, on display several years back. A woman had used it on loan and when firing it, a slug got stuck in the barrel. She didn't notice it so she kept firing it until three or four slugs backed up in the barrel. The gun never blew up, but the barrel did expand in several areas.

Jimmy W:
That a fairly common occurance that I've noted several times over the years. A word to the wise here. If you at anytime contemplate purchasing an older Colt or S&W revolver,particularly the target models, run your fingers up an down the barrel feeling for bulges. The target model tended to get used a lot and usually with handloads. One cartridge without it charge of powder will cause the scenario outlined above.
A bulge is not an automatic kiss of death and,if the prices is right, rebarreling may just get you a nice revolver at a very good price. I rescued a Colt Officers Model Match* with a bulged "Heavy Barrel" and it took some doing to find a replacement. The revolver is now good as new and a joy to shoot.

*In all likeylood we'll probably never see the like of these hand fitted and finished revolvers built again. The skilled labor cost to make them would be just too high to keep them competetive with mass assembled pistols like Glocks. So you can put these in the same category as hand crafted doubles which are financially out of reach to the general masses.
Jim