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Model 12 Barrel blowout

Discussion in 'Shooting Related Threads' started by joegriff, Aug 21, 2009.

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  1. joegriff

    joegriff Member

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    I was shooting with a friend who was shooting a Model 12 Trap 2 pin rib shotgun. We were shooting moderate hot loads. The barrel split right at the center post where the rib is pinned (attached)to the barrel, it opened up about 4 or 5 inches. I was shocked how thin the barrel was at that point of the barrel. I don't believe the loads or a obstruction had anything to do with it. Your thoughts?
     
  2. TOOLMAKER 251

    TOOLMAKER 251 Active Member

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    Would a moderate hot load be the same as a light heavy load?
     
  3. over the hill

    over the hill Active Member

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    Id bet on an obstruction.

    I used to go to a lot of Buddy shoots years ago and you wouldnt believe the shells used.

    Heavy Herco loads, XXMagnums, etc., The ground shook.

    Almost everyone then shot a 12, 870, 1100 or a BT.

    From the looks of those guns they had been shot hard; never a problem.


    Regards....Gewrald
     
  4. joegriff

    joegriff Member

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    A person familar with model 12's told us that a 2 pin rib being only attached at the center post and the rib at the receiver butting againest the rib on the barrel without the proper spacing (clearance) over time the hammering effect from recoil can cause the barrel to fail under the center post as where this barrel failed. He said he had seen this before. Anyone ever hear that before?
     
  5. Hap MecTweaks

    Hap MecTweaks Well-Known Member

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    Joe, I've never heard that before but it makes sense to me that it may possibly have some effect. I'd also think a shotgun would last many more heat/shock waves and vibrational cycles using less, not more high pressure impacting loads too?

    Dennis DeVault posted here quite some time back that shotgun barrels in a controlled fixture looked like a snake swallowing his prey. Expanding and contracting as the load traveled the length of the barrel. Hap
     
  6. scooterbum

    scooterbum Active Member

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    ("that shotgun barrels in a controlled fixture looked like a snake swallowing his prey. Expanding and contracting as the load traveled the length of the barrel.")

    Just like the old timey cartoons.
     
  7. walnutmaker

    walnutmaker TS Member

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    Joe, I've worked on them most of my life and have talked with Roger Eubanks in Idaho-------- and other than barrel obstructions I've never heard of a M12 barrel blowing up. Not to say it's impossible but I doubt it. Phil In Colo.
     
  8. Barry C. Roach

    Barry C. Roach Well-Known Member

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    Was the barrel altered, ie backbored?
     
  9. walnutmaker

    walnutmaker TS Member

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    Good guess Barry--- that would be a very good possibility! You'd need the complete history of the gun and in most cases that would be dreaming. Phil
     
  10. eightbore

    eightbore Well-Known Member

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    It's real easy to tell whether the barrel was worked on by using a bore gauge on the undamaged areas. I have heard that measuring wall thickness at the area of a burst is unreliable because the bulging causes a thinning in the specific area of the burst. It is more accurate to slice the barrel a bit and measure undamaged areas for wall thickness. Unless the burst is right at the pinned rib post, fatigue at the post should not be the culprit.
     
  11. Hap MecTweaks

    Hap MecTweaks Well-Known Member

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    eightbore, if that one specific area did actually become fatigued, explain to me why a rupture couldn't travel both ways from that point? I worked with a lot of different metals all of my working careerer and saw some very strange thing happen to metals we all take for granted. Bridges, skyscrapers and many other structures have expansion joints for a reason. Even pipe lines above ground exposed to sunlight will have a U built in line ,again for a reason.

    The amount of heat required to silver solder two different pieces of metal together as one is what? How much heat can the parent metal stand before any excess heat structurally changes the molecular structure weakening the parent metal? I know if one happens to get in a big hurry to complete any job working with heated metals, chit can and will happen!! Is it possible CG might have put any cash pressure on making, casting, milling or any other processes to the original manufacturer to further complicate a correct answer in that situation? Yup, it's highly possible!

    I said above to Joe, I'd never seen such a thing happen to a mod.12 either but it's possible it could play a part in fatiguing the metal in that area, I don't care whose logo is stamped on it either!

    Gene Hapney
     
  12. Gatguy

    Gatguy TS Member

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    I too would like to know if the barrel had been back-bored. A barrel held in a bench vise while being bored can be squeezed into an oval shape, then the unyielding round reamer can bore the sides clamped in the vise jaws thin on the clamped sides. Such a condition can possibly cause a blowout as the walls will be abnormally thin. I've worked on many M12s thru 50 years and never saw one split in the middle without an obstruction in the barrel. Yes, shotgun & rifle barrels have vibrations and harmonic zones much like a guitar string but it would take a metallurgist or a finite-element analysis engineer to determine for sure if such stresses are the cause of this failure..I'm neither!
    Dick C.
     
  13. joegriff

    joegriff Member

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    Keep in mind that the center lug (mounting post)was separated from the barrel and still attached to the rib and I believe that part if I'm not mistaken is machined on the barrel along with the other posts and the barrel was split in both directions from that point. Go figure!
     
  14. phirel

    phirel TS Member

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    Barrel damage can be cumulative over time. It requires a major obstruction to cause failure with one shot. It has been demonstrated that a loaded 20 ga shell jammed into a 12 ga barrel will not result in a catastrophic failure the first time but will damage the barrel and lead to a future failure. Very heavy loads shot through the barrel some months ago could have resulted in the rupture.

    Barrels are made of strong, but rather soft (pliable) steel. Heat can make them hard and brittle. A hard brittle area under one post surrounded by softer steel could easily eventually lead to big problems.

    In this case all we can do is make unsupported guesses. But, we seem to never hesitate to state possible reasons that are unsupported by more than what we are thinking at the time. Tomorrow our guesses could easily change.

    Pat Ireland
     
  15. phirel

    phirel TS Member

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    Hap- Are the U-joints in a pipeline to compensate for linear expansion. Another guess.

    Pat Ireland
     
  16. eightbore

    eightbore Well-Known Member

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    I'm sure that if the damaged gun is in your possession, you understand the construction of the two pin milled rib Model 12. I am sure you understand that the rib post is not part of the barrel as some think. I don't know how much pressure the rib could put on the milled in dovetail base, by I assume the pins would shear before the little dovetail base would cause a crack in the barrel. Of course, a close examination of the fracture would give more information, as would a bore measurement.
     
  17. wireguy

    wireguy TS Member

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    A friend of mine named Walt showed me a two-pin barrel today that he just blew. It blew from the dovetail base forward, just split it open, and it was very clear to me that a stress riser was created (at least based on my observation)from the dovetail being an actual part of the barrel. The barrel was shockingly thin at that point and I could see a right angle tit of metal sticking up at what appeared to be the start of the split that appeared to me to have been created by the dovetail working at that point. My suspicion is that a silver soldered dovetail would spread that load out over a wider area. I'm hoping Walt gets on here and adds his observations.
     
  18. joegriff

    joegriff Member

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    Wireguy:
    We are talking about the same gun and Guy. I was shooting with him when it happened!
     
  19. wireguy

    wireguy TS Member

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    Oh..........................LOL!
     
  20. eightbore

    eightbore Well-Known Member

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    How about that bore measurement? We would also be interested in pictures of the fractured area. Thanks.
     
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