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.204 Ruger Complete Upper Receivers

AR15Parts.com builds .204 Ruger complete upper receivers to order for varmint hunters and precision shooters who demand extreme velocity. Every upper is assembled, headspaced, and function-checked in our shop. The .204 Ruger is one of the fastest commercial cartridges available, pushing 32-grain bullets past 4,200 fps and 40-grain bullets to 3,600+ fps. This extreme velocity translates to a laser-flat trajectory that makes hitting small targets at 300+ yards remarkably easy. For dedicated varmint hunters, the .204 Ruger on the AR-15 platform is a devastating combination of speed, accuracy, and semi-auto follow-up capability. Configure your .204 Ruger upper with your choice of barrel length, handguard, muzzle device, and optional BCG and charging handle.

Why Shooters Choose AR15Parts.com for .204 Ruger Uppers

Every .204 Ruger upper is assembled in-house with precision barrels that deliver the bore consistency this velocity-dependent cartridge demands. Headspaced, inspected, and built to your specifications. No FFL required.

How to Choose the Right .204 Ruger Upper

Barrel Length & Gas System

.204 Ruger uppers are available in 20" and 24" barrel lengths with a rifle-length gas system. Longer barrels are recommended to maximize the cartridge's extreme velocity potential. A 24" barrel is the top choice for dedicated varmint use. The 1:12 twist rate stabilizes the lightweight 32-40 grain bullets used in this cartridge.

Complete Upper vs. Barreled Upper

Complete uppers include the dedicated .204 Ruger BCG and charging handle. A dedicated bolt is required, so a complete upper is recommended for first-time builders.

Key Specifications

Muzzle Velocity: \~4,225 fps (32gr), \~3,625 fps (40gr) Effective Range: 400+ yards Barrel Twist: 1:12 Recoil: Very light Platform: Standard AR-15 lower receiver

.204 Ruger Upper Compatibility

The .204 Ruger uses a dedicated .204 Ruger bolt in a standard AR-15 carrier. Dedicated .204 Ruger magazines are required. The upper fits any mil-spec AR-15 lower.

Best Uses for .204 Ruger Uppers

The .204 Ruger is a dedicated varmint hunting cartridge. Its extreme velocity makes it devastating on prairie dogs, ground squirrels, and groundhogs with minimal pelt damage — important for fur hunters. Coyote hunters benefit from the flat trajectory that simplifies holdover at 300+ yards. The cartridge is not recommended for deer-sized game. It is purpose-built for small varmints and predators where velocity and flat trajectory matter most.

Frequently Asked Questions

What is included in a complete .204 Ruger upper?

Complete uppers include the upper receiver, barrel, gas system, handguard, and muzzle device — assembled and headspaced. Dedicated BCG and charging handle available as add-ons.

Will a .204 Ruger upper fit my AR-15?

Yes. Our .204 Ruger uppers fit any standard mil-spec AR-15 lower receiver.

Can I use my 5.56 BCG?

No. The .204 Ruger requires a dedicated bolt.

What is the .204 Ruger best for?

Dedicated varmint hunting — prairie dogs, ground squirrels, groundhogs, and coyotes. Its extreme velocity and flat trajectory make hitting small targets easy.

What is the effective range?

The .204 Ruger is effective for varmint hunting to 400+ yards.

How fast is the .204 Ruger?

The .204 Ruger pushes 32-grain bullets to 4,225+ fps, making it one of the fastest commercial cartridges available.

How long does shipping take?

Most in-stock configurations ship within 3-5 business days. Custom builds may take 2-3 weeks. Orders over $99 ship free.

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