Bulgarian 8x56R question

I was going through a large number of these when I noticed what seems to me a presence of beveled surface on the outer portion (closest to rim) of the headstamp of 1940,1941 and 1942 while 1938 and 1939 seem to have flat headstamps. Am I imagining things? If no, why that bevel was installed in subsequent years?

There is a beveled surface and there seems to be no pattern, it is found on other manufactures also, I WAG is that it is part of the forming stage which varies slightly.

Another other question is why some manufactors have an oval primer and others are flat other that what they had on hand?