the so odd shaped crimp is a standard on every military 6.5 carcano ammo loaded with the ordinary FMJ bullet with the large cannelure (until 1936-1940).I don’t know the reason of that odd shape,however the large cannelure has a odd shape itself.
My first idea was that the double crimp was for a transitional bullet model between the old type with that large cannelure and the 1940 model with a smaller cannelure.This bullet has both types of cannelures.However,some guys said me that they have some 1912,1918 and 1924 carcano ammo with the double crimp,so they can’t be loaded with a bullet adopted several years later.
The 3 point crimp is not a good crimp because the bullet is often free to move into the neck[/quote]
I looked at some 6.5mm Carcano’s that I have to see if it was date related. I found the following:
SMI 928 with the double crimp
SMI 929 with the double crimp
BPD 34 with the double crimp
BPD 36 with the triple neck crimp only
SMI 936 with the double crimp
BPD 949 with the mouth crimp only and a knurled cannelure visible on the bullet
So there is no obvious date related reason for the different crimps.