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338 ARC Complete Uppers

A 338 ARC upper brings heavy .338-caliber performance to the AR-15 platform, combining impressive subsonic capability with hard-hitting supersonic ammunition. Built for compatible AR-15 rifles, a 338 ARC upper is an excellent choice for suppressed shooting, hunting and shooters who want heavy-bullet performance from the compact AR-15 platform.

Read More About Our 338 ARC Uppers

A 338 ARC upper gives shooters the familiar controls, compact dimensions and modularity of the AR-15 while supporting heavy .338-caliber projectiles. The cartridge is designed to deliver effective performance with both supersonic and subsonic ammunition, making a 338 ARC AR-15 upper particularly well suited to suppressed shooting, hunting and specialized heavy-bullet applications.

Every Ballistic Barn 338 ARC complete upper receiver is built to order with carefully selected components and configuration options. Each 338 ARC upper assembly is assembled in-house, individually checked for proper headspace using Manson GO and NO-GO gauges, and inspected for fit and function before shipping.

Configure your 338 ARC upper receiver with your preferred barrel length, profile, handguard, receiver finish, muzzle device, adjustable gas block, compatible bolt carrier group and charging handle to create a 338 ARC complete upper suited to your intended ammunition and application.

The 338 ARC is designed around the AR-15 platform, but it requires caliber-compatible components rather than a standard 5.56 NATO bolt and magazine configuration. Before completing your build, confirm barrel, bolt, magazine, muzzle-device and ammunition compatibility for your specific 338 ARC AR upper configuration.

Heavy .338-Caliber Performance for the AR-15

Why Choose a 338 ARC Upper?

A Ballistic Barn 338 ARC upper delivers impressive .338-caliber energy in the AR-15 platform. It is an outstanding option for hunters, suppressed shooters and anyone wanting a compact rifle capable of launching heavy bullets efficiently.

Designed Around Heavy .338-Caliber Bullets

The 338 ARC combines modern bullet design with AR-15 compatibility to provide excellent retained energy, efficient suppressed performance and strong terminal capability while maintaining manageable recoil.

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Supersonic & SubsonicDesigned for both hunting and suppressed applications.
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Heavy BulletsOptimized for high-mass .338-caliber projectiles.
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AR-15 PlatformLarge-caliber performance in a familiar AR-15 platform.
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Headspace CheckedEvery upper is verified with Manson GO and NO-GO gauges.

Compatible Components Required

The 338 ARC requires a compatible 6.5 Grendel-type bolt and magazines. Always verify compatibility before ordering.

Why Buy From Ballistic Barn?

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Individually Headspace Checked
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Built in Fredericksburg, Texas
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Configurable Component Options
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Inspected for Fit and Function

Every Ballistic Barn upper is assembled in-house with carefully selected components and individually inspected before shipping.

338 ARC Upper Specifications and Compatibility

FeatureSpecificationWhy It Matters
Caliber338 ARCHeavy .338-caliber performance in the AR-15 platform.
PlatformAR-15Fits compatible AR-15 lower receivers.
Common Barrel Twist1:8Supports heavy .338-caliber bullets.
BCG CompatibilityAR-15 carrier with 6.5 Grendel-type boltRequired for proper bolt-face dimensions.
Gas SystemMatched to barrel lengthSupports reliable cycling.
Muzzle ThreadTypically 5/8x24Compatible with many .30-caliber/.338 suppressor mounts; verify listing.
Magazine Compatibility6.5 Grendel-pattern magazinesRequired for reliable feeding.
Ammunition TypesSupersonic and subsonicSupports hunting and suppressed use.

338 ARC Upper FAQs

Does the 338 ARC upper come ready to use?

Every Ballistic Barn upper is assembled, inspected for fit and function, and checked for proper headspace using Manson GO and NO-GO gauges before shipping. Review each product listing for included components.

Is a 338 ARC upper compatible with a standard AR-15 lower?

Yes. It is designed for the AR-15 platform but requires the proper 6.5 Grendel-type bolt and compatible magazines.

What bolt does a 338 ARC use?

A compatible 6.5 Grendel-type bolt installed in a standard AR-15 carrier.

What magazines are used?

Compatible 6.5 Grendel-pattern AR-15 magazines are typically required.

Is 338 ARC good for suppressed shooting?

Yes. The cartridge was designed with excellent subsonic capability while also supporting supersonic hunting ammunition.

Is 338 ARC good for hunting?

Yes. With appropriate supersonic ammunition it is well suited for deer, hogs and similar game where lawful.

What barrel length is best?

Many shooters select 12.5- to 18-inch barrels depending on whether compact suppressed performance or maximum velocity is the priority.

What twist rate is common?

A fast twist such as 1:8 is commonly used to stabilize heavy .338-caliber bullets.

Does it use a standard AR-15 bolt and magazine?

No. It requires a compatible 6.5 Grendel-type bolt and magazines.

How does 338 ARC compare with 300 Blackout?

The 338 ARC was designed to deliver greater downrange energy and heavier high-BC projectiles while retaining excellent suppressed capability, though component requirements differ.

Why buy a 338 ARC upper from Ballistic Barn?

Every upper is assembled in-house, inspected, and individually headspace checked using Manson GO and NO-GO gauges.

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