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The Pro2A 13.7" 5.56 NATO Mid Length Non-Reciprocating (NR) Side Charging Upper Receiver offers the perfect solution for operators searching for the absolute shortest rifle-length footprint without stepping into NFA short-barreled rifle regulations. Chambered in the universally trusted 5.56 NATO (fully backward-compatible with .223 Remington), this premium upper features a muzzle device that is permanently pinned and welded to the barrel threads to legally satisfy the 16-inch federal requirement. Shifting traditional rear charging charging motions over to an ergonomic side mechanism, it is paired with a smooth-cycling mid-length gas operating block for significantly reduced felt recoil and minimized component wear.
| Upper Receiver | Patented Gibbz Arms G4 Billet Aluminum Non-Reciprocating Side Charging Upper Receiver, AR-15 Format, M4 Feed Ramps, Type III Hardcoat Anodized Finish |
|---|---|
| Charging System | Left-Side Non-Reciprocating Charging System (Static Handle Design) with Standard Right-Hand Ejection Pattern |
| Barrel Length & Profile | 13.7-Inch Government Profile (Brings overall barrel length to a legal 16-inches via pinned and welded muzzle device) |
| Caliber | 5.56 NATO (.223 Remington Compatible) |
| Twist Rate | 1:7 Twist |
| Barrel Material & Treatment | 4150 Chrome Moly Vanadium Steel, Premium Corrosion-Resistant Melonite Finish |
| Gas Operating Block | Mid-Length Direct Impingement, 0.750" Low-Profile Steel Gas Block, Stainless Steel Gas Tube |
| Muzzle Thread & Device | 1/2x28 Thread Pitch, "Pro2A Flash Guardian 3 Prong Flash Hider" Permanently Pinned & Welded to ATF Compliance Standards |
| Handguard Rail | 12" Slim Free-Float M-LOK Handguard, Machined from 6061-T6 Aluminum with Top Picatinny Rail Layout |
| Manufacturing Origin | 100% Made in the USA with Pro2A Tactical Lifetime Factory Warranty |
Shooters wanting the maximum handling advantages of a short-barreled carbine without legal restrictions pick this 13.7-inch build. The permanently attached muzzle assembly preserves a true rifle classification while dramatically cutting front-end weight.
Operators looking for a reliable, soft-shooting platform choose the mid-length gas system configuration. It extends the longevity of standard cycling components, lowers the mechanical strain on internal parts, and keeps muzzle rise highly predictable.
Custom gunsmiths aiming to update a standard small-frame lower into an innovative, heavy-hitting utility weapon choose this complete upper. It snaps easily onto mil-spec lower assemblies, bypassing home assembly risks.
| SKU | P2ANR556AX12MID137-BA-PW |
|---|---|
| Barrel Length | 13.7 inch |
| Rifle Caliber | 5.56 NATO |
| Manufacturer | Pro2A Tactical |
