AR-15 Uppers & Complete Upper Receivers

Why Shooters Choose AR15Parts.com for Upper Receivers

Every AR-15 upper we sell is assembled in-house using components from brands shooters already trust. We don't just warehouse and ship — we build each upper to your exact specifications, test headspace, and inspect every assembly before it leaves our shop. Here's what sets AR15Parts.com apart:

• 19+ caliber options — from mainstream 5.56 NATO and .300 Blackout to specialty rounds like .224 Valkyrie, .22 ARC, .50 Beowulf, .458 SOCOM, and .204 Ruger. No other shop offers this caliber depth in a single catalog.
• Premium barrel manufacturers — Wilson Combat, Ballistic Advantage, Satern, and Faxon barrels standard across our lineup. No generic or unbranded barrels.
• Built to order — choose your barrel length, gas system, handguard, and finish. We assemble it, verify headspace, and ship. Not pulled off a shelf — built for your specific configuration and handguard specification your build requires.

How to Choose the Right AR-15 Upper

Selecting an AR-15 upper receiver comes down to five decisions. Get these right and the rest of your build falls into place.

1. Purpose — What Will You Use It For?

Your intended use determines nearly every other spec. A home-defense AR pistol upper has completely different requirements than a precision varmint upper or a general-purpose carbine. Before looking at barrel lengths and calibers, decide whether this build is primarily for home defense, range use, hunting, competition, or duty/patrol. That single decision narrows your caliber, barrel length, and gas system choices dramatically.

2. Caliber Selection

AR15Parts.com offers uppers in 19+ calibers because no single cartridge does everything well. Here's a simplified framework:

• General purpose / home defense: 5.56 NATO / .223 Wylde or .300 Blackout. The 5.56 is the most versatile AR-15 cartridge with the widest ammo availability and lowest cost per round. The .300 Blackout excels in short barrels and suppressed builds.
• Precision long range: 6.5 Grendel, .224 Valkyrie, or .22 ARC. These cartridges push the AR-15 platform past 800 yards with match-grade loads while staying inside a standard AR-15 lower receiver.
• Hunting (medium/large game): .350 Legend, 6.8 SPC, .450 Bushmaster, .458 SOCOM, or .50 Beowulf. Straight-wall options like .350 Legend and .450 Bushmaster are legal in states that restrict bottleneck cartridges for deer hunting.
• Varmint / predator: .204 Ruger, .22 Nosler, or .223 Wylde with a fast-twist barrel. Flat trajectories and minimal recoil for quick follow-up shots.
• AK-pattern ammo in an AR: 7.62x39. Uses widely available and affordable steel-case ammo. Requires an enhanced firing pin and specific bolt/barrel combination — all included in our 7.62x39 complete uppers.

3. Barrel Length & Gas System

Mid-length gas systems are the current standard for 16" barrels — lower port pressure means softer recoil, less bolt carrier velocity, and longer part life compared to carbine-length. Mid-length gas systems are the current standard for 16" barrels — lower port pressure means softer recoil, less bolt carrier velocity, and longer part life compared to carbine-length.

4. Complete Upper vs. Barreled Upper vs. Stripped Upper

Understanding what's included prevents surprises:

At AR15Parts.com, our standard listings are complete uppers — BCG and charging handle included — so you're not hunting for compatible parts after checkout.

5. Barrel Material & Profile

The barrel is the single most important component of any upper receiver. It determines accuracy, weight, heat dissipation, and service life.

• 4150 CMV (Chrome Moly Vanadium): Mil-spec standard. Extremely durable, holds up to sustained fire and suppressor use. Ideal for duty, defense, and general-purpose builds.
• 416R Stainless Steel: The precision shooter's choice. Slightly better mechanical accuracy potential than CMV, preferred for match and varmint builds. Trades some barrel life for tighter groups.
• Chrome-lined: Chrome lining inside the bore and chamber extends barrel life significantly and improves corrosion resistance. Slight accuracy trade-off vs. non-lined barrels, but negligible with modern manufacturing.

For barrel profile, government and mid-weight profiles offer the best balance of accuracy, weight, and heat management for most shooters. Heavyweight barrels add weight but improve sustained accuracy.

AR-15 Upper Types Explained

AR-15 Rifle Uppers

Rifle-length AR-15 uppers feature barrels of 16 inches or longer and are the most versatile configuration. A 16-inch mid-length gas system is the most popular combination in America for good reason: it balances velocity, accuracy, maneuverability, and parts longevity. Our rifle uppers are available in every caliber we carry, with barrel lengths from 16 to 20 inches.

AR-15 Pistol Uppers

AR pistol uppers are barrels shorter than 16 inches and are designed for use with a pistol brace or as registered SBRs. Popular configurations include 7.5", 10.5", and 11.5" barrels in 5.56 NATO and .300 Blackout. Short-barreled .300 Blackout uppers are particularly effective suppressed, as the cartridge was designed for short barrels and reaches full powder burn in as little as 9 inches. AR15Parts.com carries pistol uppers from 7.5" to 14.5" across multiple calibers.

AR-10 / .308 Uppers

For shooters who need the power of a .308 Winchester or 6.5 Creedmoor in a semi-auto platform, our AR-10 uppers deliver. Built on the larger DPMS-pattern receiver, these uppers are not interchangeable with standard AR-15 lowers. Check your lower receiver pattern before ordering.

AR-15 Uppers by Caliber

Every caliber below is available as a complete upper receiver from AR15Parts.com. Click any caliber to browse available configurations.

• 5.56 NATO / .223 Wylde — The standard. Widest ammo selection, lowest cost per round, effective to 500+ yards.
• .300 Blackout — Purpose-built for short barrels and suppressors. Subsonic and supersonic loads available.
• 6.5 Grendel — Long-range precision in an AR-15. Effective past 800 yards with match ammo.
• .224 Valkyrie — Flat-shooting, low-recoil precision cartridge optimized for long-range competition.
• .22 ARC — Hornady's newest entry for long-range AR-15 precision. Excellent ballistic coefficient in a compact package.
• 7.62x39 — AK-pattern ballistics in an AR-15. Affordable ammo and hard-hitting at close to medium range.
• .350 Legend — Straight-wall cartridge legal for deer hunting in restricted states. Effective to 200 yards.

Frequently Asked Questions