Can you eventually give me an advise for the Griefmaster Achievement? I have all online ones except this one. I am choosing the map Canyon with 3 AI opponents and shooting birds and boars like hell. When I see a red perk, I'll sprint for it to get it. I use it right away on any of the AI but I don't get the achievement at the end of the match. The 4 perk one was easy, but it seems to be that there are no 8 different perks on the map.