Quick note explosive mines are found in gadgets and cost 1000 of the weird Dimond things you get from playing games. This is alot easier than it sounds, while this achievement can work on ANY item you can pick up and throw, your best bet without a doubt is an explosive canister (the red tube shaped ones). I'd recommend using a medium or heavy character to survive more gunfire while lining up your shot. I'm gonna be honest the mine being set off is inconsistent asf and you will probably want to try this indoors. When looking for a target don't try it on a full health heavy as it will not be enough to kill them. All in all this achievement is more luck than skill but it's far from impossible and shouldn't take an absurd amount of attempts took me maybe a couple hours of attempts but obviously you could get luckier than I did.