I didn't think it was an issue either until I saw an x-ray of a carcass killed with lead and copper bullet. Lead fragments had spread way beyond the wound entry area to the tune of 10 or more inches.
MnDNR sheep test?
Those photos I have seen. I can see the cases of extreme spread of the lead in some of those shots and can see where it is pretty reasonable once you understand that most of the lead s very, very fine particles that are nether visible nor palpable. A hit will lift the onside hide and separate it some from the underlying tissue. Extremely small particles would likely form a cloud intermixed with blood and finely ground tissue/bone and the whole mess could be well and widely disseminated. Witness the "pink mist" when you splatter a varmint. It''s logical to assume that both the entrance area and the exit area would show some of that dispersion along with the wound path through the middle.
One of the significant problems though is the blood inside the cavity has to be assumed to be well contaminated. When you gut, the is no way to avoid contaminating OTHERWSE uncontaminated areas like the hams and tenderloins even in the case of a through the chest double lung shot.. I have never seen any Xray or otherwise analytical attempt at shedding light on that problem.
While there undoubtedly would be bacterial contamination of meat after a bullet passes through there is a lot to consider if we get into that issue.
