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Mean Arms
The Mean Arms Bearing Delay 9mm upper receiver with 11-inch barrel is a complete, ready-to-run 9mm AR platform solution built around a proprietary ball-bearing delayed blowback system. This is a modular upper assembly—pair it with any standard AR-15 lower receiver (milspec or dedicated pistol-magazine type) and you're ready to shoot. Unlike traditional roller-delay designs, Mean Arms' three ball bearings deliver 50% more contact surface area than a single roller, meaning greater durability and reliability even under the higher pressures of modern ammunition. It's a proven delay method stripped of outdated engineering.
The 11-inch barrel is threaded 1/2-28 for a muzzle device and comes paired with Mean Arms' own recoil- and flash-reducing muzzle brake. The included MA handguard uses a rigid hybrid design—polymer body with an overmolded metallic insert—tuned for the 11-inch configuration and free-floated for accuracy. The slick-side billet aluminum upper receiver meets milspec standards, the ambidextrous MA charging handle combines steel and aluminum construction, and the bolt carrier group can be tuned by swapping the included Lifters to adjust the delay curve for different ammunition types or suppressor use. The system runs on standard AR-15 buffers, meaning no exotic parts or proprietary components beyond the upper itself.
Two Ejectorless EndoMags come in the box, along with two Lifters for tuning. This upper is purpose-built for shooters who want 9mm AR reliability and familiarity without compromise—whether you're running suppressed, unsuppressed, or swapping ammunition loads. The bearing delay architecture keeps recoil low and reliability high across the platform.
| Caliber | 9×19mm Parabellum |
| Barrel Length | 11 inches |
| Muzzle Thread | 1/2-28 |
| Upper Weight | 3.23 lbs |
| BCG Weight | Just under 11 oz |
| Handguard Internal Width | ~1.375 inches (flat to flat) |
| Lower Receiver Compatibility | Milspec AR-15 and dedicated 9mm pistol-magazine types |
| Buffer Compatibility | Standard AR-15 buffers |
The Mean Arms 11-inch Bearing Delay upper pairs with any milspec AR-15 lower receiver. It's also compatible with dedicated pistol-magazine 9mm lower receivers; most will need the stationary ejector removed to work with this system. The included Ejectorless EndoMags eliminate the need for the upper's center ejector to function with those builds.
No. The Bearing Delay system uses standard AR-15 buffers—there is no 9mm-specific buffer requirement. This keeps your parts bin simple and your build cost-effective.
Each upper includes the complete assembled receiver, billet aluminum upper, free-float MA handguard, ambidextrous MA charging handle, MA muzzle device with jam nut, two Lifters for tuning the delay curve, and two Ejectorless EndoMags. Magazines are not included with the EndoMags.
The system is tuned by replacing the Lifter, which changes the angle of the surfaces that interface with the ball bearings inside the bolt carrier group. You can adjust the delay curve based on ammunition type, barrel length, suppressor use, or other factors. Two Lifters are included to get you started.
Mean Arms
The Mean Arms Bearing Delay 9mm upper receiver with 11-inch barrel is a complete, ready-to-run 9mm AR platform solution built around a proprietary ball-bearing delayed blowback system. This is a modular upper assembly—pair it with any standard AR-15 lower receiver (milspec or dedicated pistol-magazine type) and you're ready to shoot. Unlike traditional roller-delay designs, Mean Arms' three ball bearings deliver 50% more contact surface area than a single roller, meaning greater durability and reliability even under the higher pressures of modern ammunition. It's a proven delay method stripped of outdated engineering.
The 11-inch barrel is threaded 1/2-28 for a muzzle device and comes paired with Mean Arms' own recoil- and flash-reducing muzzle brake. The included MA handguard uses a rigid hybrid design—polymer body with an overmolded metallic insert—tuned for the 11-inch configuration and free-floated for accuracy. The slick-side billet aluminum upper receiver meets milspec standards, the ambidextrous MA charging handle combines steel and aluminum construction, and the bolt carrier group can be tuned by swapping the included Lifters to adjust the delay curve for different ammunition types or suppressor use. The system runs on standard AR-15 buffers, meaning no exotic parts or proprietary components beyond the upper itself.
Two Ejectorless EndoMags come in the box, along with two Lifters for tuning. This upper is purpose-built for shooters who want 9mm AR reliability and familiarity without compromise—whether you're running suppressed, unsuppressed, or swapping ammunition loads. The bearing delay architecture keeps recoil low and reliability high across the platform.
| Caliber | 9×19mm Parabellum |
| Barrel Length | 11 inches |
| Muzzle Thread | 1/2-28 |
| Upper Weight | 3.23 lbs |
| BCG Weight | Just under 11 oz |
| Handguard Internal Width | ~1.375 inches (flat to flat) |
| Lower Receiver Compatibility | Milspec AR-15 and dedicated 9mm pistol-magazine types |
| Buffer Compatibility | Standard AR-15 buffers |
The Mean Arms 11-inch Bearing Delay upper pairs with any milspec AR-15 lower receiver. It's also compatible with dedicated pistol-magazine 9mm lower receivers; most will need the stationary ejector removed to work with this system. The included Ejectorless EndoMags eliminate the need for the upper's center ejector to function with those builds.
No. The Bearing Delay system uses standard AR-15 buffers—there is no 9mm-specific buffer requirement. This keeps your parts bin simple and your build cost-effective.
Each upper includes the complete assembled receiver, billet aluminum upper, free-float MA handguard, ambidextrous MA charging handle, MA muzzle device with jam nut, two Lifters for tuning the delay curve, and two Ejectorless EndoMags. Magazines are not included with the EndoMags.
The system is tuned by replacing the Lifter, which changes the angle of the surfaces that interface with the ball bearings inside the bolt carrier group. You can adjust the delay curve based on ammunition type, barrel length, suppressor use, or other factors. Two Lifters are included to get you started.
