The serial number range is what a 'sneak' should be "u" suffix.
Its mismatched. Although your close up pictures are good, you took internal shots which just show maker markings, which don't help us much
A sneak is a late DWM parts, so would not expect a Mauser frame.... Please see the FAQ for what a sneak is. They are not just police, they are a left over contract that was never sent out.