Is that really necessary? The gut shot should cause them to bleed out. Somewhat slowly. Seems like you are wasting a perfectly good round.
We should ask the Apaches about how to terminate them. The Apache Indians had numerous ways to enact slow painful death on their captives.
A bullet is too good. Hanging is too good. I laugh at lethal injection. They need to be skinned alive, staked out in the desert sun next to a fire ant hill and have honey poured over them. This for starters.
Well, you could look at it that way, but a long drawn out slowly aimed head shot where they could see, even with their gut shot and groin hurt, would give them some sense of dreaded finality. I’d do it.