To be 90%sure of, they must not have much of the bullet left over to examine. So fragmentation must have occurred, or the bullet must have passed thru and is not yet recovered.
Entry wounds from small caliber would be almost indistinguishable, the soft tissue destruction
is proportionate to the projectiles velocity.
Exit wound gives an idea of the retained weight
and diameter. So its an educated guess that 5,56 was used, does the Ruski 5,54 fragment?
Does a .223 from an AR have any distinguishing characteristic where a 222, 222 mag, 22-250, 224 Trophy can be excluded when loaded with the same bullet at velocities known to produce extensive fragmentation? What about a .223 bullet in a sabot out of a 30-06?
This is a AR witch hunt. I for one refuse to pay the price for some homicidal maniac who has slaughtered innocent people in cold blood. The outrage should be directed against what he did, not what instrument was handy........Lebrew