forgive, the case length gage is referred to as being drop-in, the go-gage is used to check a chamber for go-gage length, I do not find it necessary to own one or the other, I make gages, I make gages to measure gages.
Today? I am going to make a gage that will measure the length of a 50 Cal. chamber, any 50 Cal. 2 different ways. I will not research Sammies ideal of a perfect chamber, because? Sammie is not sizing the cases.