The .204 Ruger is a high-velocity small-caliber centerfire cartridge introduced in 2004, firing a tiny .204-caliber bullet at very high speed. With an exceptionally flat trajectory and very low recoil, it is a specialized varmint and predator cartridge.

The .204 Ruger was introduced in 2004 by Ruger and Hornady, designed around an unusually small .204-caliber (.20 caliber) bullet driven at very high velocity. It set out to be a premier varmint cartridge by maximizing speed and flatness, and on introduction it was among the fastest production centerfire cartridges available. Ballistically the .204 Ruger fires a very light bullet — commonly around 32 to 45 grains — at extremely high velocity, producing an exceptionally flat trajectory with very low recoil and minimal report relative to larger varmint rounds. That flatness and low recoil let a shooter spot their own shots and make precise hits on small targets at distance, which is the heart of its appeal for varmint and predator hunting. Its tradeoffs are those of a specialized small-bore: it is suited to small targets rather than larger game, light bullets can be more affected by wind despite the flat trajectory, and like other high-velocity small bores it can show accelerated barrel wear. Its rifle and ammunition availability is steady within the varmint-shooting niche. Today the .204 Ruger is used for varmint and predator hunting and target shooting, with steady availability among varmint-oriented rifles and ammunition. Its combination of extreme velocity, a very flat trajectory, and very low recoil is why it became a favored specialized varmint cartridge.

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