herman the shocker has several photos of rifle , shotgun and other suicides. some photos you can see where the bullet entered.
this site has images with exploded heads so don't view if sensitive to this
New York. These photos depict a close-up of the victim and the extensive damage inflicted by the high velocity blast
www.hermantheshocker.com
the problem is in that link they give the rifle but not the ammunition. i need to know the exact ammunition and rifle to have the same effect instant Death for me. there just isn't enough data so i have to take a risk that the particular ammo rifle or shotgun combination would will work. in general i think most rilfe and shotguns in the mouth aimed at the brainstem would do it for me. also to the side of head aimed at the brain stem. main thing is not to flinch . in the mouth less likely to flinch especially if grip gun with teeth deep in mouth. seems like 99% to me
also watch people die website has many videos of shotgun and other suicides