The 338 ARC (Advanced Rifle Cartridge) is a modern centerfire cartridge from Hornady designed to deliver heavy .338-caliber bullets, including subsonic loads, from the compact AR-15 platform. It is oriented toward suppressed shooting and moderate-range hunting.

The 338 ARC is part of Hornady's Advanced Rifle Cartridge family, designed to extend the platform's versatility by driving heavy .338-caliber bullets from the compact AR-15. A central design focus is its suitability for both supersonic and heavy subsonic loads, the latter pairing well with suppressors for quiet shooting — a role that has grown in popularity. Ballistically the 338 ARC is built around relatively large-diameter bullets for its platform class, offering effective performance at moderate range and notable flexibility between supersonic hunting loads and heavy subsonic suppressed loads. Within the AR-15 size class it provides a heavy-bullet option distinct from the platform's smaller-caliber standards, with the practical benefit of using the familiar AR-15 architecture. As a very new cartridge, its rifle and ammunition selection is at an early stage relative to established rounds, though it is backed by Hornady and the broader interest in suppressor-friendly and platform-versatile cartridges. Today the 338 ARC is positioned for suppressed shooting, moderate-range hunting, and recreational use in the AR-15 platform, with an early but growing base of support. Its pairing of heavy .338-caliber bullets and subsonic capability with AR-15 compatibility is what distinguishes it as a recent specialized entry.

General information about this caliber — not a recommendation for this specific firearm.