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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.
Cross Machine Tool Upur-4 Billet AR-15 Upper Receiver - Slick Side
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.
Updated · from real builds on GunPartPicker · Prices checked · refreshed daily across 35 retailers
We ranked every upper receiver by how often it shows up in real builds on GunPartPicker.
Read the guide: Most Popular AR-15 Upper Receivers →Check it against the live catalog:
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Builds in the community that include the Cross Machine Tool Upur-4 Billet Ar-15 Upper Receiver - Slick Side
| Build | Parts | Total |
|---|---|---|
![]() | 14 | $2476.77 |
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