TheHunter: Call of the Wild Wiki

"A .300 magnum caliber polymer-tip bullet that is configured for high penetration and superior aerodynamics. The .300 magnum caliber is known for it's high velocity and pin-point accuracy, which makes it a good choice for long-range shots on very large game such as moose, gemsbok, and brown bears."
― In-Game Description

The .300 Magnum Polymer-Tip Bullet is a type of ammunition available for the .300 Canning Magnum family of rifles.

This ammo is available as part of the Yukon Valley DLC.