Excellent point WRT wear due to trap movement and I certainly agree with the comment regarding foundries and Foundrymen. The pattern number, if it is that, would support the notion that it was likely foundry produced. It is interesting others have not been encountered. The rifle is a generic, albeit quite well done, sported service rifle that has not been otherwise customized. I would not expect to find a one-off custom made component such a rifle, but that could well be the case.