Mike did a good job. Here are a few more (all dates approximate):
Before 1910
1910-1920 Square butt
1910-1920 Round butt
1920-1929
1930-1941
1935-1946
1946-1953
1953-1966
1967 and later
What I can't show you is the plastic medallions that were used for a brief time in the early 1950s. I don't own any so I cannot take a picture of them. Someone else here may have such a photo.
Also, there were two different sizes used on service stocks in the 1930s. Those shown above are the smaller of the two. I don't have any with the large medallion. Sorry.