Apex Legends' Season 4: Assimilation has brought a ton of changes, with the addition of Sniper Ammo type being just the tip of the iceberg. Sentinel, however, is a peculiar beast that takes some thoughtful planning to utilize best.
The first and most obvious thing for Apex Legends' new sniper is charging it up, and you do it by pressing the Toggle Fire key, which on PC is B by default.
Each charging up of the Sentinel sniper or energising as Respawn call it, takes one shield battery from your inventory, which is quite the trade-off you need to make. Apex Legends players know that the batteries aren't exactly a dime a dozen across the map, so this requires some planning.
Sentinel's energised state decays over time, and loses a chunk of juice with each shot, but more importantly - the state makes it a real shield killer.
Note that the shield damage is the same regardless of where you hit your Apex Legends adversary, so going for headshots is pretty much pointless. Sentinel's headshots will do 130 damage whether you charge it or not.
"While energized, the Sentinel fires projectiles that deal massive damage to shields. The projectiles use different VFX trails, and there is a unique energized firing sound, so all nearby players know that the Sentinel is firing these higher damage projectiles", Respawn wrote.
Respawn continue to polish Apex Legends' meta and the Sentinel definitely looks like a weapon that will take teamwork to utilise to the max, while still being simple enough to use for beginners. In the hands of a single player on a well-oiled team, though, it's almost like a spare, EMP-like ultimate.