Tried the Deadly Accuracy achieve many times, even again today, killed >50 spiders each time, tried during metas, and cannot get achieve to complete. Both other achieves for rifle are done. In my opinion, its not quite the same as the focus issue. For focus, i got all 3 sub-achieves completed, but since reward for one achieve wasn't correct, the main achieve for focus didn't show complete (which they fixed by allowing those who got achieve to get reward item from vendor). Here, for rifle, you can't seem to get credit for kills to complete achieve.