PUBG: BATTLEGROUNDS (EP)

As of 10/08/2018 this achievement does not track properly - however it is still possible to obtain.

The only assault rifle's that appear to track kills towards this achievement are the M16A4 and the M416. The distance (100 meters away) is not required, feel free to kill enemies from any range; what you MUST do - to progress this achievement - is make sure you are aiming down the IRON SIGHT. I have tried aiming with a red dot sight on numerous occasions and not once has it tracked the kill. 6x scopes appear to work on occasion but they are not consistent. At this time the only sure fire way to progress this achievement is using the weapons iron sights.

I have not been able to test every sniper rifle but can confirm that the VSS, Winchester, Mini 14, and M24 do not count towards this achievement, even from a distance greater than 100 meters.

This seems to be glitched but in a good way (if achievements work at all for you in this game)

Any kill, regardless of distance, with an Assault Rifle or Sniper Rifle will count towards this.

Note: if in a team game simply knocking down an opponent does not count, you must also get the kill with the weapon