2-Piper,
As noted in the letter, to put the strain gauge on the barrel wall over the adapter itself (as it would be at 1 in. from the breech) would give falsely low pressure readings because the adaptor would be absorbing much of the strain in that location, although I agree with your statement. The paragraph about the problems with locating the strain gauge in regard to the adaptor length explains this. It is a pity that there is no clear apples to apples comparison with regard to ammo brand and measurement locations.
However I believe, but do not know, that there is more to the story than in the letter. I discussed these tests with him over two years ago when I asked him the very question that the original poster asked here. He told me about the tests, but at the time was reluctant to have his name associated with them because it was contracted work for the manufacturer. I gathered that they might have been hoping to show a pressure reduction as well as good patterns, but were not able to, so the pressure discussion was intentionally absent in advertising literature. I also believe (but again, do not know) that he may have been personally hoping to show a pressure reduction for the benefit of the vintage gun enthusiast. I believe additional testing was done, but isn't in the letter because it wasn't useful to the manufacturer (can't show a pressure decrease) nor harmful (because they never claimed decreased pressure). I do know that his answer to me was a very direct "no" in regard to any significant pressure decrease. I have kept this information to myself until this moment, when for the first time I have seen at least some of the results published and signed by him. Given his straight-forward manner in answering me, and his usual thorough manner, I believe he probably has more data to draw his conclusion from than presented here, and likely would include at the least an apples to apples comparison of ammo from the same manufacturer.
Just my thoughts.
