https://www.pcgamer.com/fortnites-new-heavy-sniper-is-real-and-can-one-shot-metal-walls/

Last month, data miners at Fortnite hub Storm Shield uncovered an item entry for a new "heavy" sniper rifle capable of shooting through walls. Yesterday, the Fortnite Battle Royale Leaks Twitter shared some early footage of the gun in-game, confirming that the heavy sniper is not only on the way, but that it can destroy even metal walls in one shot.  

The item entry found by Storm Shield says the heavy sniper rifle fires rounds that pierce the first wall they hit, but an in-game teaser spotted by the Fortnite Battle Royale News Twitter simply says it is "capable of dealing high damage to structures." That said, the weapon stats shown in the video above line up with the stats listed in the entry, so it's possible the heavy sniper can outright pierce walls as well as destroy them—that it to say, obliterate a wall and the dude behind that wall with one shot.