Stripped AR15 Upper Receiver

Stripped AR15 Upper Receiver from GorillaMachining.com: The 2025 Complete Guide

Want to build your own AR-15 platform with precision, flexibility, and cost control? A stripped AR15 upper receiver from GorillaMachining.com gives you a clean, high-quality foundation to assemble your ideal rifle. This guide covers everything you need — specs, benefits, compatibility, finishing options, purchase advice, and best practices.

What Is a “Stripped AR15 Upper Receiver”?

A stripped upper receiver refers to just the receiver housing without the internal components (bolt carrier group, charging handle, barrel, handguard, gas system, etc.). It is “bare bones,” enabling custom builds.

Using a stripped upper, you select your barrel, BCG, gas system, and accessories, letting you tailor performance, weight, and aesthetics.

GorillaMachining offers a selection of stripped upper receivers in both raw and anodized finishes. 

Why Choose GorillaMachining’s Stripped Uppers?

Here are the compelling advantages of going with GorillaMachining:

• Forged 7075-T6 Aluminum: Their receivers are machined from mil-grade 7075 aluminum forgings for strength. 

• MIL-Spec M4 Feed Ramps: The designs include proper feed ramps to reliably support common AR barrels.

• Multiple Finishing Options: Available in raw, anodized, or Cerakote styles. 

• Wide Variety of Calibers: Their inventory includes uppers compatible with 5.56/.223, 300 Blackout, .458 SOCOM, .450 Bushmaster, 6.5 Grendel, and more. 

• Competitive Pricing: Their M4A4 stripped upper is listed for under $40 in raw finish. 

• Customization Friendly: Because it’s stripped, you can install your chosen barrel length, gas system, handguard, BCG, and accessories.

Key Specifications & Design Features

Below are typical specs you’ll find in a GorillaMachining stripped upper:

These features make it compatible with most standard AR-15 parts and accessories, and provide a solid foundation for customization.

How to Use a Stripped AR15 Upper Receiver

When you purchase a stripped upper from GorillaMachining, here’s how you build around it:

1. Barrel Selection
   Match the caliber and twist rate you plan to shoot (e.g. 1:7, 1:8, 1:9). Ensure the barrel has an M4 extension if using M4 feed ramps (which is standard).

2. Gas System & Gas Block
   Choose the correct gas length (pistol, carbine, mid, rifle) based on barrel length. Use a low-profile gas block that fits under your handguard.

3. Bolt Carrier Group (BCG)
   Select a BCG (nitride, phosphate, or nickel boron finish) that’s compatible with your caliber. The stripped upper allows you to install your preferred BCG.

4. Charging Handle
   Standard mil-spec or ambidextrous—choose based on your preference.

5. Handguard / Rail System
   Free-float handguards mount to the barrel nut underneath; drop-in rails are also workable depending on your build.

6. Muzzle Device
   Thread the barrel with the correct muzzle device (flash hider, muzzle brake, compensator, suppressor adapter).

7. Assembly and Torqueing
   Mount the upper, torque the barrel nut per spec, align gas block, and ensure proper timing.

With the stripped upper, you control every part of the build.

Advantages & Disadvantages

Advantages:

• Full customization control — Choose every component you want

• Cost-effective entry point — Stripped uppers are cheaper than complete uppers

• Modular upgrade path — Easily upgrade barrel, handguard, or BCG later

• Lightweight and minimalistic — No extra mass from preinstalled parts

Disadvantages:

• Requires tools and know-how — You need proper tools and gunsmithing skills

• Time investment — You must source and install all parts yourself

• No plug-and-play — You’ll need to assemble before the upper is functional

Pricing & Market Context

GorillaMachining offers stripped upper receivers with pricing typically in the $30 to $60 range, depending on finish and style. 

For example, their Gorilla Machining AR-15 M4A4 Stripped Upper Receiver RAW is listed at about $38.99 on their site. 

This pricing makes stripping and customizing your AR build quite economical when compared to buying a fully complete upper with all components.

Comparisons with Complete Uppers & Alternatives

Best Practices & Tips When Buying & Building

• Check for machining quality: Look for tight tolerances and no machining defects.

• Verify compatibility: Ensure the receiver matches your barrel and parts’ feed ramps and style.

• Choose the right finish: Raw is cheapest and best for custom coating later; anodized or Cerakote adds aesthetics and corrosion resistance.

• Inspect rails and top edges: The MIL-STD 1913 top rail must be straight and flat for optics alignment.

• Use quality torque specs and tools: Proper torque ensures alignment and longevity.

• Test fit before final assembly: Ensure parts like BCG, dust cover, forward assist, etc., fit correctly.

Legal And Compliance Notes

A stripped upper receiver is not a firearm and typically does not require FFL transfer in the U.S. It’s essentially a raw part. But:

• Be mindful of local and state laws regarding AR builds.

• If you eventually install a barrel under 16", you may require registration or tax stamp depending on jurisdiction (SBR rules).

• Always abide by BATFE and federal firearm regulations in your area.

Final Thoughts

The stripped AR15 upper receiver from GorillaMachining.com is an excellent entry point for custom AR builds, offering flexibility, high-quality materials, and great value. With the right parts, tools, and assembly knowledge, you can build a rifle tailored to your exact preferences—whether for competition, defense, or recreational shooting.

From raw aluminum options to prefabricated anodized or Cerakote finishes, GorillaMachining gives you a solid, customizable foundation for your AR platform.