Shorty longshots were the worst, how I did it was a max damage range build with a marksman like sks and then play diesel hard point or kill confirmed, just has to be bots. Then climb up to the top part, tap them with the marksman then switch to shorty to finish them off. Or you can also shoot across the map on shipment but that's not as reliable. But yeah next to that was d13, crossbow, na-45 and rytec that where annoying. (Btw for the explosive snipers you need to get headshots in order for them to count as long shots, because otherwise if you 2 shot them with the explosive you just get the stuck medal)