The scholar who chastised me for bringing up wall thickness gauges as a trump for eighty year old proof marks also made a comment about "Very seldom is striking the cause of bad wall thickness. Drilling 'em out from the inside is usually the reason." (I just assumed it was the same guy, I didn't check) That is so much BS. I can measure and examine the inside to determine what has been done in there. The hidden cause of bad wall thickness is eighty years of incompetent UK striking. Bad behavior in the bore can be detected with a ninety dollar bore micrometer. I will stick to my opinion that proof marks are worth nothing if you don't measure. "Sleeved" not marked on a water table does not take the place of close examination of the barrels with a high powered glass. Sure, it's nice if the mark is there, but if it isn't there, you had better get out your glass before you get out your checkbook.