Maxim Defense Industries MDX 508 U.R.G. AR-15 .300 AAC Blackout 8.5 inch Upper Receiver Pistol Length 1-7 Twist 5/8x24 HATEBRAKE Black

Name: Maxim Defense Industries MDX 508 U.R.G. AR-15 .300 AAC Blackout 8.5 inch Upper Receiver Pistol Length 1-7 Twist 5/8x24 HATEBRAKE Black
Brand: Maxim Defense
Availability: InStock

Maxim Defense · Upper Receiver

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Best price

$1,255.50at OpticsPlanet

In stock Sale checked Oct 13, 2026

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Store	Price	Availability	Buy	Add to build
OpticsPlanet Best price	$1,255.50Salechecked Oct 13, 2026	In stock	Buy at OpticsPlanet
MidwayUSA	$1,255.50checked Oct 13, 2026	In stock	Buy at MidwayUSA

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Lowest in-stock price in the last 30 days: $1,255.50 at MidwayUSA. Dashed line = out of stock. Tracking since Oct 12, 2026.

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Store	Latest	Lowest	Highest
MidwayUSA	$1,255.50	$1,255.50	$1,255.50
OpticsPlanet	$1,255.50	$1,255.50	$1,255.50

Since Oct 12, 2026.

About this part

The Maxim Defense Industries MDX 508 U.R.G. AR-15 .300 AAC Blackout 8.5 inch Upper Receiver Pistol Length 1-7 Twist 5/8x24 HATEBRAKE Black is an 8.5" 300 Blackout upper receiver from Maxim Defense. It's sold by 2 stores, all at $1,255.50. The lowest in-stock price in the last 30 days was $1,255.50 at MidwayUSA.

Fits and works with

Caliber: 300 Blackout · Shop matching ammo
Bolt: Standard AR-15 (5.56 / 300 BLK / .350 Legend) · Bolt carrier groups
Gas system: Pistol · Handguards
Muzzle thread: 5/8x24 · Muzzle devices
Barrel length: 8.5" · Handguards

Specifications

Manufacturer: Maxim Defense
Color: Black
Platform: AR-15
Caliber: 300 Blackout

From the manufacturer

Maxim Defense Industries MDX 508 U.R.G. AR-15 .300 AAC Blackout 8.5 inch Upper Receiver Pistol Length 1-7 Twist 5/8x24 HATEBRAKE Black. It features an 8.5 barrel making it ideal for close-quarters situations. The included HATEBRAKE increases reliability and is tucked under the 9.5 handguard. These upper receiver groups ship complete including a Maxim Defense Mil-Spec or SCW bolt carrier group Radian Raptor charging handle and Maxim Defense hand stop ready to shoot right out of the box Specifications for Maxim Defense Industries MDX 508 U.R.G. AR-15 8.5 inch Upper Receiver: Manufacturer: Maxim Defense Industries Overall Length: 17.5 in Barrel Length: 8.5 in Muzzle Device: Hatebrake Finish: Cerakote Handguard Style: M-LOK w/ Top Picatinny Rail System Gun Model: AR-15 Barrel Material: 4150 Chrome Moly Vanadium Features of Maxim Defense Industries MDX 508 U.R.G. AR-15 8.5 inch Upper Receiver 1. Increased reliability due to included HATEBRAKE 2. Armorer level adjustable gas block 3. M-slot compatible handguard 4. Military-grade materials 17-4 Stainless Steel 7075 and 6061 Aluminum 5. HK height rail for a more rigid upper receiver 6. Installs on any Mil-Spec lower receiver 7. Comes with Mil-Spec or PDX BCG Package Contents: Maxim Defense Industries MDX 508 U.R.G. AR-15 8.5 inch Upper Receiver What firearm models does the manufacturer say Maxim Defense Industries MDX 508 U.R.G. AR-15 8.5 inch Upper Receiver is compatible with? The manufacturer suggests that Maxim Defense Industries MDX 508 U.R.G. AR-15 8.5 inch Upper Receiver is compatible with AR-15Maxim Defense Industries MXM-47929: MDX 508 U.R.G. AR-15 .300 AAC Blackout 8.5 inch Upper Receiver Pistol Length 1-7 Twist 5/8x24 HATEBRAKE Black