So, here is a weird one. It is a 1943 knife as far as I can tell. It came in the big collection I bought last year and was one of only two I kept.

It is a screw on butt cap, no nut!

While the idea eliminated the nut and washer, it probably did not work well since any tightening of the butt cap would have would have left the butt cap out of alignment with the washers.

There are two known examples of this style butt cap. Mine and the pictures of the other knife that had the but unscrewed and pictures taken. Mine has not been disassembled.

First, my knife, you can see in this picture there is no nut on the butt cap.



These next few are from a different knife that was disassembled: