Simply a guess but I'd imagine they added the extra step as you put it for reliability in detachable box magazine fed guns. The crimp will hold the bullet in place under recoil as well as neutralize the forward inertia of the bullet as an automatic bolt slams the cartridge into battery.
I shoot both the cannelured and non cannelured 77smk and I do not notice a difference. My long range where im at though is 300-400yds.
The shape of the tmk cannelure though is arrowhead shaped and it is on the ogive of the bullet it appears so it must effect BC at some range but again my guess is no significant difference.
Edited to add: I dont crimp any of my 77gr smk with or without a cannelure.
I shoot both the cannelured and non cannelured 77smk and I do not notice a difference. My long range where im at though is 300-400yds.
The shape of the tmk cannelure though is arrowhead shaped and it is on the ogive of the bullet it appears so it must effect BC at some range but again my guess is no significant difference.
Edited to add: I dont crimp any of my 77gr smk with or without a cannelure.
Last edited:












