HomelessiOe,I did not intend to imply that the Proof houses are at fault.It is not unreasonable to expect that the Proof houses would seek to absolve them selves from responsibility for failures due to inappropriate test proceedures.This issue begs a response from the London and Birmingham Proof Masters and the Guardians of proof.[Majority of the later being members of the gun trade.]
If there was a defect in any gun that failed at proof; dimensional,material or in the manufacturing process, the Proof house did its job in protecting the end user from an unsafe weapon.
I think we would all rest easier with the knowledge that the Proof Houses have been absolved from any responsibility in the failures reported.

Roy Hebbes