well unless there is contamination from the ground or other surface in the bullet, I dont see how that can necessarily be a given.

for example

Unlike other tissue simulants, that used at the Letterman Army Institute of Research(10% ordnance gelatin shot at 40C has been shown to reproduce the bullet deformation and fragmentation pattern seen in living animal muscle 11-31. Although the gelatin calibration was done using muscle, it has recently been found to show similar results in soft tissue shots of the abdomen as well.
Since bullet deformation in tissue is a function of the velocity with' which it enters the tissue,

from http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA188670&Location=U2&doc=GetTRDoc.pdf

Bullet deformation is also fairly likely in shots into the chest cavity from Impact with bones.

Any idiot can face a crisis - it's day to day living that wears you out.