I'm not sure if this will help, but it is here for your review. I pulled my Mosin bolts and photographed them. One photo is with flash and the other without. The bolts are identified from left to right as
1934 Izhevsk 91/30 hex, all matching
1948 Izhevsk M44 round, all matching
1945 Izhevsk M44 round, all matching
1930 Tula 91/30 hex, all matching
1936 Tula 91/30 round, matching bolt/receiver
I included the information reference "matching" so you would know that the year of the bolts are confirmed by the year on the matching receiver.
I didn't include my 1941 M-39 with matching bolt/hex receiver.
Hope it helps!
Attachment 120267Attachment 120268