Far Cry Primal

The Club, Bow, and Spear all have achievements for hitting 100 kill count. Depending on your personal preference, you'll pick up at least two achievements for the weapons without really trying.

TIP - The Longbow will let you stay out of range of other enemies, and it does some decent damage. If you want guaranteed death, I've not seen anyone survive a hit with the double bow (Elite's excepted)

TIP - I believe that your takedowns will count towards the kill count. You can see your selected weapon being used for the takedown. If I or another player confirm this, I'll update the solution.

This achievement requires the killing of 100 enemy tribesmen or beasts through the use of the bow. The easiest way to increase this count is once you get the longbow as it allows you to kill from further away without alerting enemies. This gives you more opportunity for snipe or bow kills.