Cockney Rebel, I too am intrigued.If I was asked to carry out ANY test I sure as hell would check the calibration of the test equipment, including any 'outsourced' supplies.I find it very difficult to believe that 'proof' loads had been erroneously loaded.I believe that the Proof Houses absolve themselves of all responsibilty for errors and omissions.In other words 'Bad luck Nige 'Ole Chap'.Never mind 'the boys' may get a few hours overtime out of that one.Look on the bright side that pair could always be sold with a pair of spare barrels by the original maker! ! ! !