doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Disaster struck yesterday

It's hard to be sure from the picture but the split in that barrel looks to have edges that are real thin.

I know the remaining metal may be stretched but it would be interesting to know thw wall thickness. It may be a case of excessive polishing out of pits at some point in its years...

Jeff

Fred, look carefully at Deltaboy' pic, do you see two longitudinal scratches inside the bbl? I guess the same type stratch was the cause.

eightbore:

I'm assuming by reference to the "chicken/egg" you concur with Jones that the crack changed the relationship of sear to hammer notch and "caused" the second of the two discharges? Most interesting interpretation that's come up in this potpouri discussion. Now what am I looking at thru the crack in the eBay S/W bar?

jack

RE; case coloring vs case hardening. Case hardening is done by heating a piece of low carbon steel to a temp above it's critical temp in a carbon rich mixture which causes the metal to absorb carbon into it's surface. Depth depends upon both temp & time. It is then quenched in water while still above the critical temp which causes hardening of the carbon rich surface "case" to take place. The colors are a by-product of the process from oxidation of the surface & when done with intent to produce the colors is often referred to as "Color Hardening". Loss of color does not indicate loss of hardness as the case is much deeper than the colors.
I believe, but not totally sure, the colors can be formed with the temp a little below the critical temp. This greatly lessens the possibility of warpage, shrinkage etc, "BUT" however leaves the steel in a near annealed condition. I firmly believe the makers put that hard case on there for a definate purpose. Personally, I would never have a frame annealed without re-hardening it. Either have a professional who knows about heat treating do the proper Color-Case Hardening, or forget it. The other acceptable process is the one I have posted about which I call "Pseudo Case Coloring". This is done using cold blue streaked on with part at about 160°F. while not producing as good a color as desirable for a high grade gun, it is perfectly safe.

Gosh, I was still replying to the question about the broken Fox. Sorry if I didn't seem to be responding to the blown up barrel situation. The "broken Fox guy", in my opinion, should be weighing his powder in all remaining shells, and he should also be naming his case hardening guy and asking him some questions. Coincidence of a broken action after an oven job is too much to swallow. Either find some funny shells or come clean with the "color guy".

I've got more pictures. But the gun is at a gunsmith. I will send him the link to this thread. Maybe he'll come on some time. But 2 piper I didn't think you were disabusing an Elsie, that's why I posted the pics.:)
Deltaboy

On the Fox, I have to wonder as did another poster if the frame did not perhaps fail first and the 'double' was, in fact, a very quick second shot that simply further opened the crack. I am also assuming that the gun had double triggers, but don't know that for a fact as it was not stated.

On the Elsie w/the bbl split, I have seen some realy nasty gouges in some bbls that had early steel shot loads fired through them. Some of the early steel shot loads did not have very strong wad petals and the shot would scrub completely through the plastic and gouge the bbl. I'm not saying that is what happened, only that it might be a possible cause. I have also heard of gravel and other things being loaded in lieu of lead shot in times past in the days of card and fiber wads.

I have seen several old Ithacas with lateral scratches in their bbls., but I had/have no way of determining the causal factor[s] that put them there.

I recall a situation where battery elecrolyte could in some situations contact the very hard carbon steel of a motorcycle chain and if it did, the side plate would crack causing a catastrophic chain failure. That failure [crack] could be duplicated on the bench in a static contamination test with zero load involved! Just something to keep in mind about compatibility of certain materials and chemicals.

Lastly, cracks can often be examined by someone trained in such matters to determine the 'nature' of the crack or 'type'. Fatigue cracks are generally dif in appearance from catastrophic failure cracks and or chemical caused cracks, but not always. Just some thots.

Very glad that you were not injured. Your Fox can be replaced.

We have two situations with the Fox failure that are notable. Situation #1: "I'm sure all the shells were OK." Situation #2: I don't think were going to get any more information on the casehardening person, who is "local and advertises nationally". Not to be sarcastic about the unfortunate shooter/Fox owner, but we are being told nothing about the two situations that are most important to the gathering of information. In short, measure the powder and give up the name of the gunsmith.

Geno, I honestly can't see the scratches you do. It may be because I'm using a notebook (IBM T30). The screen is good, but probably not as sharp as a large, first-class monitor.

Jack, two other thoughts come to mind, but they are just speculation. First, if the first shot produced seriously abnormally-high recoil, that acceleration alone could possibly cause the second sear to disengage. Second, if the crack was opened by the first shot (abnormally heavy or not), and altered the sear-to-bent geometry, that could cause disengagement.

I agree that KNOWING what's in ALL the remaining shells is critically important. If I were doing it, I'd send three to Tom Armbrust.

Regarding the post-color casing condition of the receiver, either insufficient annealing before color-casing, and/or quench from too high a temperature could seriously pre-dispose a frame to cracking. Here are two posts by Oscar on the subject:


Re: Re-Case Coloring and Steel warpage? (J. Stephens)
Date: Tue, 14 Oct 1997 00:28:18 GMT
From: Oscar Gaddy <o-gaddy@ux1.cso.uiuc.edu>
Yes indeed, warpage and shrinkage can occur with color casehardening, but with proper precautions and pretreatment, it can be minimized to practically no problem at all. I believe that Peter Johnson's book refers to the hard fitting that Roy described in more detail. I have been told that Frank Lefever, at one time, had the jigs and fixtures used by Parker Bros. for this purpose. The new owners of Lefever Arms may or may not still have them--I know that they sold the Parker barrel rib milling machine about two years ago.

The most significant cause of warpage is the internal stresses that pre-exist in the part that is hardened. The quenching from a high temperature can exacerbate these stresses and causes warpage. To eliminate this, I always anneal by heating parts to be re-case hardened in a controlled atmosphere to 1500 degrees F for one hour and then slowly cooling for several hours to room temperature. This treatment relieves all internal stresses and diffuses the carbon in the hardened surface layer throughout the material leaving the parts as dead soft as virgin mild steel. Even with this precaution, thin parts such as tangs will tend to warp and, to prevent this, I use spacer fixtures around the tang screws to hold the top tang and trigger plate tang in the same relative position with respect to each other during the quench. Another cause of warpage and shrinkage is quenching from too high a temperature. I use the lowest quench temperature that is possible to obtain the proper hardness and the correct colors. Using these precautions, I very seldom have any problems with warpage and shrinkage and proper fitting after color casehardening. The only time I usually have any problems are with frames that have previously been casehardened several times. In these cases, minor shrinkage can occur which sometimes requires carefully removing some metal from the barrel breech faces for proper fitting or stoning close tolerance areas such as the bolt slot on Parkers for proper clearance.

I suspect, but cannot prove, that if gunmakers such as Parker had annealed their frames prior to final finishing, engraving and case hardening, they would have had much less warpage problems and would have required much less hard fitting. These frames were drop forged, subjected to machining and filing and probably bending all of which would tend to create internal stresses in the steel which can amplify warpage during color casehardening.


More On Color Casehardening
Date: Aug 02, 20:57
From: Oscar Gaddy <o-gaddy@uiuc.edu>
I agree with many of your comments but disagree with several. Your description of the casehardening process is correct for what is called martensitic hardening that is used in industry for hardening parts that are subject to extreme wear. This type of casehardening occurs when the carburized part is quenched from a temperature above the critical temperature of approximately 1340 degrees F. This produces maximally hard surfaces, but unfortunately also usually produces severe deformation and warpage of irregularly shaped parts such as gun frames. It also tends to produce microscopic cracks that can be stress concentration points and result in more cracking and frame breakage in severe cases. This warpage and cracking is due to an approximate 2 % expansion of a martensitically hardened case because of the change in crystal structure of martensite. This type of hardening can be and is used in many industrial processes with appropriate steps taken to account for the warpage and cracking, but cannot be and should not be used on firearms. Consequently, gun parts are usually casehardened by carburizing at above the critical temperature and then the temperature is lowered to slightly below the critical temperature before quenching. If the carburizing is done at a temperature of about 1400 F., very high carbon percentages are produced in the case and upon quenching from below the critical temperature, martensite is not formed, a large percentage of cementite (iron carbide) is frozen into the case and the case is very (file ) hard with very little or no warpage. While the case produced in this manner is not as hard as martensite case, it is more than ample for firearms. In industrial casehardening, wood charcoal is used with an energizer such as barium carbonate. In bone charcoal casehardening for firearms, the tri-calcium phosphate that constitutes about 80 % of bone charcoal acts as the energizer producing the carbon monoxide needed for efficient carburization.