Cross Machine Tool

Cross Machine Tool Upur-4 Billet AR-15 Upper Receiver - Slick Side

Cross Machine Tool Upur-4 Billet Ar-15 Upper Receiver - Slick Side - Upper Receiver for AR-15 - view 1
Cross Machine Tool Upur-4 Billet Ar-15 Upper Receiver - Slick Side - Upper Receiver for AR-15 - view 2
Cross Machine Tool Upur-4 Billet Ar-15 Upper Receiver - Slick Side - Upper Receiver for AR-15 - view 3
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Cross Machine Tool

Overview

The Cross Machine Tool Upur-4 Billet AR-15 Upper Receiver is a stripped slick side upper designed for builders looking for a clean and streamlined aesthetic. Made from billet aluminum, this upper offers a solid foundation for your AR-15 platform, ensuring durability and precision in your assembly. It's particularly popular among multi-caliber builds, providing versatility for various shooting applications.

Specifications

MPNUPUR-4
MaterialBillet Aluminum
Receiver TypeSlick Side
AssemblyComplete
PlatformAR-15

Available Merchants(1)

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Primary Arms
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In Stock
$140
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Build history on GunPartPicker

Builders on GunPartPicker first added the Cross Machine Tool Upur-4 Billet AR-15 Upper Receiver - Slick Side to a build in March 2026.

Availability is good: it was in stock at one retailer or another nearly every day in August 2026, and today the one retailer we track has it in stock. Prices barely moved in August 2026, holding around $140, so there haven't been real sales lately. Buying today, the lowest price is $140 at Primary Arms, which matches the best price we saw in August.

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Frequently Built With

The part most often added in each category by the 3 builds that include this one

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Gas Tube$17in 1 build
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Bolt Carrier Group$199in 1 build
Radian Weapons AR-15 Raptor SD-SL Ambidextrous Charging Handle Black

Radian Weapons AR-15 Raptor SD-SL Ambidextrous Charging Handle Black

Charging Handle$111in 1 build
Ballistic Advantage 14.5" .300 Blackout Pistol Length Barrel, Modern Series

Ballistic Advantage 14.5" .300 Blackout Pistol Length Barrel, Modern Series

Barrel$158 · out of stockin 1 build
Superlative Arms AR-15 Adjustable Gas Block .750" Clamp on Melonite

Superlative Arms AR-15 Adjustable Gas Block .750" Clamp on Melonite

Gas Block$81in 1 build

Builds Featuring This Part

See all 1 →

Builds in the community that include the Cross Machine Tool Upur-4 Billet Ar-15 Upper Receiver - Slick Side

BuildPartsTotal
for hog hunting 10.5" build
for hog hunting 10.5"		14$2476.77

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