As there has been a flurry of postings about re-proofing guns, I thought I should give a heads-up on a rather worrying development at the UK proof houses.
Lately there had been rumours of guns 'unexpectedly' failing proof including some from our most illustrious makers which I doubt is a common occurrence!
Although there have been tales of actions failing, it seems that the majority of these failures have been caused by barrels bulging just behind the chokes. The choke constrictions in these cases have apparently all been in excess of a UK 1/2 or 0.020" and all instances have been with 12b guns, smaller bores seem unaffected.
After several 'unexpected' failures, one barrel specialist asked for a formal investigation of the proof loads that were being used as it is alleged that the start of these problems coincided with a change in the sourcing of the loads used by both Proof Houses. The subsequent reply from the Proof House confirmed that they had tested their proof loads and had found no problems with them.
I have heard it suggested that as they test pressure only at 1" and 6" from the breech face, they are most likely looking in the wrong place but not being a ballistic expert I do not know if this hangs together.
I would stress that I have not been a victim of this problem, in fact I have never had a gun fail proof 'unexpectedly', maybe because I seldom work on guns with heavy choke, and I am sure that the proof houses are working hard to discover if there really is a problem. However, I feel that now is perhaps not the best time to be considering a re-proof of your pride and joy! Best to wait until this has all been sorted out.
