BCC

Jay, I also generally agree with BillM and others opinions on the Black grips/un-numbered mags relating to the u serial block and beyond. You should however keep in mind that new items and parts (ie black grips, black mag bottoms) were almost always introduced somewhat gradually into the production line. This is certainly true on most items that can be dated to certain production times for the German military. After a change in style or material (ie laminated stocks for k98k) was tested and accepted, then orders were placed and quanities started trickling in to the assembly lines. These were incorporated into the assembly..and so on. My point is, while noticeable quanities of black grips may not have been delivered to start being used until the u block, this does not mean that small quanities ( say a few hundred) were not being used up here and there several months earlier. As implied above this is certainly the case on the laminated k98k stocks and many other weapon changes.

I agree that the un-numbered alum. bottom mag probably would have still be numbered in the s block. The used of the black bottom mag could be same as the grips.