Need help identifying two mill bits. The first looks similar to a woodruff seat cutter. The second appears to be a countersink bit but the corkscrew flute pattern is unusual. Not sure what type holder would be used with the second bit.
Looks like a countersink to me. Back in the ''old days'' some of the cutters screwed in to the holder. I've never actually seen the screw in holders. Kind of looks like a Whitworth thread with the round bottoms.