I have always wondered how a LEO could tell if the loads used in a shooting were or weren't factory loads. If I shoot a box of Remingtons and reload them I sure forensics (FBI) could tell they where reloads. But why would they examine them.
After examining your loading bench and load data, perhaps? But your question remains valid even then.
I think it's more likely that
you would tell
them.
If the evidence and testimony are sufficiently clear and consistent and support the story of a self-defense claim, no one will care.
But consider a close-range shooting with contradictory evidence and testimony. You testify that the shooting occurred at X feet. The person you shot and someone who was with him says the distance was 3X feet. The state investigator testifies that there was little or no gunshot residue on the person, and the state's expert witness testifies that factory loads of the type apparently used would leave GSR on the target at X feet but little or none at 3X feet. Test data that you cannot use as evidence for reasons that have been discussed at length prove that the hand loads that you used would not have left material amounts of GSR on the target at X feet.
What's at stake? Possibly two things. The first is your credibility; if you are perceived to be lying about the distance, how believable is the rest of your story? The second may impinge on whether a reasonable person would have believed that he was in imminent danger; at X feet, maybe yes, but at 3X feet maybe not--the old A, O, J determination.
With the state's evidence and expert witnesses indicating a distance of 3X feet, you could be in a world of hurt without a way of countering that evidence and testimony.
If an armed man with whom you have had no prior dealings breaks through your door at night and you use deadly force, your case should be very solid almost anywhere.
If you are accosted by someone elsewhere and have to shoot, and there are credible witnesses who saw what happened and are willing to come forward, good for you.
What I worry about is the incident that unfolds fast and you shoot, the person turns out not to have been armed, there are no credible witnesses who saw anything other than you standing with a gun in your hand and someone else on the ground, and it boils down to a matter of your word against that of the two or three persons whom you believed to constitute a serious and immediate threat.
Any evidence that would support your side of the story could prove crucial.
Looks as if Daryl beat me to it.