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Aero Precision M4E1-T PRO Upper Receiver Group — 16" KB (APUG700021D1071) — Informational Overview
The Aero Precision M4E1-T PRO Upper Receiver Group is a factory-assembled upper receiver unit built around Aero Precision’s M4E1 receiver architecture. This configuration is listed as a 16-inch upper in KB (a color designation used in some catalogs), identified by part number APUG700021D1071 and UPC 840014626670. Upper receiver groups are typically used as complete front-end assemblies for compatible AR-style platforms, combining major components into a single unit (exact included items can vary by SKU and listing source).
Because “upper receiver group” packaging differs between manufacturers and retailers, users typically confirm what is included for this specific part number—such as handguard type/length, gas system configuration, muzzle device details, and whether a bolt carrier group and charging handle are included—by referencing Aero Precision’s official product description for APUG700021D1071.
Key Identifiers
Manufacturer: Aero Precision
Product: M4E1-T PRO Upper Receiver Group
Barrel Length (as listed): 16 inches
Color (as listed): KB
Part Number / MPN: APUG700021D1071
UPC: 840014626670
M4E1 Receiver Architecture: General Context
Aero Precision’s M4E1 line is commonly associated with an enhanced receiver pattern used across their AR-style components. Depending on the specific “PRO” configuration, the upper receiver group may incorporate receiver and handguard interface features intended to support consistent assembly and compatibility with standard AR-pattern parts, within the constraints of the included rail/receiver design.
For practical compatibility, users typically verify:
Fit with the intended lower receiver
Handguard mounting system used on the “PRO” configuration
Any model-specific features that may affect parts selection or assembly
16" Barrel Length: Common General-Purpose Configuration
A 16-inch barrel length is widely used in AR-style rifles because it often offers a balance between handling and ballistic performance, depending on chambering, gas system, and ammunition selection. In many jurisdictions, 16" is also a common compliance benchmark for rifle barrel length (laws vary), which can simplify configuration considerations compared with shorter barrels.
Actual performance depends on the barrel’s specific specs (twist rate, chamber, gas system length), ammunition, and the full system setup.
“KB” Color Designation: Appearance Notes
This product is listed as KB. Because color codes can vary by retailer catalog and manufacturer naming conventions, users who care about finish matching commonly verify:
What “KB” stands for in the listing context (e.g., a specific color name or finish family)
Whether the receiver, handguard, and other included components share the same finish process
Whether minor shade differences should be expected between different materials or production runs
If color matching is important, checking manufacturer reference images or a seller’s detailed description for APUG700021D1071 is often helpful.
What “Upper Receiver Group” May Include (Verify by SKU)
The contents of an “upper receiver group” can vary. Depending on this SKU’s bundle, it may include some or all of:
Upper receiver
Barrel assembly
Gas block and gas tube
Handguard/rail system
Forward assist and ejection port cover (if applicable)
Muzzle device (if included; details vary)
Bolt carrier group (BCG) and charging handle (sometimes included, sometimes sold separately)
Because these inclusions affect compatibility and setup, confirming them for APUG700021D1071 is recommended.
Installation, Safety, and Compliance Notes
Upper receiver groups are function-critical firearm components. Safe use typically requires:
Compatibility checks with the intended lower receiver and parts
Correct assembly and torque specifications where applicable
Appropriate function checks after installation
Compliance with all applicable firearm laws and regulations
If unsure about fitment, assembly, or compliance details, many owners consult a qualified armorer or gunsmith.
Quick Reference Summary
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