I have reviewed the pictures of the barrel failure and have made the following observations.
1/If the shell pictured was a standard Remington 12 G. Trap load the breech pressure to be expected would be in the order of 10,000 P.S.I. This is much too high for a damascus barrel. [As others have pointed out;"LOW BRASS DOSE NOT EQUAL LOW BREECH PRESSURE".]
2/Looking at the deformation of the shell, It is my opinion that the actual pressure was far in excess of 10,000 p.s.i[ie; See Burrard, The Modern Shotgun, Vol,3 page 408, for pictures a shell damaged due to excessive pressure.]
3/ The rupture/tearing of the shell case and the damaged wads seen in the pic;suggests that there was a possibility that fragments of a shell case or wad from the previous shot could have been lodged in the barrel immediately ahead of the forcing cone. If this was the case, a wave pressure would have been generated this would have the effect of increasing pressure at point of failure by more than 200%.
4/The barrel as seen in pics; 2&3 indicates that the welding of the barrel coil[breech end] was unsatisfactory.The weld clearly lacks penetration.This defect will act a stress raiser when the barrel is under pressure.This is most likely the primary point of the barrel failure.
5/Other pictures show what appear to be serious metal defects, namely ,lamination and a crystaline structure, both of which would have a negative impact on the ultimate strength of the barrel.
6/ In pic;7 We can see evidence of pitting, but more importantly in pics; 14 & 21 it appears as though rust has developed in the faulty barrel weld and also under the barrel rib.The fragment of the barrel that was recovered is also very rusty. However this could have occured after the failure.
SUMMARY
The probable cause of failure was an incorrectly loaded shell that resulted in excessive breech pressure. A partial obstruction in the barrel due to fragments of a shell case or wad being lodged in the barrel immediately ahead of the forcing cone is a distinct possibility. This being the case, wave pressure build up would occur.The high breech pressure,combined with the defects in welding, poor metal chemistry, lamination, pitting and rust resulted in the catastrophic failure seen in the pictures.
I think the poster here essentially got it right so I really don't have much to add but this. I know you damascus fans are in denial here but I think it's apparent that a faulty technology coupled with faulty manufacturing here was a big contributor to this failure. Lets all be thankful no one got hurt but shooting damascus barrel guns is IMO a crap shoot.
BTW: That M1 pictured above came apart on the first shot with re-loads of unknown origin. I suspect improper re-sizing with the bolt failing to go completely into battery as being the cause here.
Jim
