Tungsten Bullet

This is the Tungsten world's answer to the Silver Bullet, and the Arms Dealer only stocks the metal your world actually generated. In the seeds that contain both, he looks at which ore has more blocks placed and sells that one, and he checks again every time the world loads. The stock can flip between sessions without you doing anything.

Before Hardmode this is Blood Moon stock only, so the night you want to be buying in bulk is the night that is trying to kill you. Plan a run to him with your coins already sorted. Once Hardmode starts it is permanent stock and stops being something you schedule around.

It hits slightly harder than the basic round and pushes enemies further than the Silver equivalent does, and you pay for both. Knockback is the real difference, and it counts most on slow weapons where every shot has to buy you space. On something with a high rate of fire the extra cost per round outruns the benefit.

Several guns ignore what you loaded and convert basic rounds into a different projectile entirely, so feeding one of those the pricier ammunition is money thrown away. Check what your gun does with a plain musket ball before committing to a full stack of these.