https://www.polygon.com/2018/8/2/17644252/pubg-pc-update-19-patch-dynamic-weather-bullet-penetration

The newest update for PlayerUnknown’s Battlegrounds on PC, update 19, is live. Now that the PUBG Global Invitational has come to a close, developer PUBG Corp. is back to making big improvements to the game.

One change in this patch is something players have been asking about for a while now: bullet penetration. What this means in PUBG is that bullets will now go through certain parts of players, like their arms or hands, and hit other areas that will do more damage. It may sound like a small change, but it actually makes quite a big difference. What would have been otherwise good shots could have most of their damage mitigated, simply because a player’s arms happened to be in the right spot at the right time. That often frustrates the player doing the shooting.