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CMMG Upper-M4LEP-II 5.56/.223 16"No Sights - 55BE184


You will receive fast, free shipping for all orders over $35

Shipping cost is $5.50 for orders under $35. We ship with UPS and USPS. 

Most orders ship out within 24 hours

You will receive tracking information immediately at the time of shipment. To expedite shipping, we may ship your order from multiple warehouses.  

We have a 90-day no-hassle return policy. We pay return shipping.

If you need to request a return, contact us at and we will send you a return label

After 90 days, defective items will still be covered under the manufacturer’s warranty, where applicable.

Please refer to the product listing for warranty details. If you have specific warranty questions, contact us at We may direct you to pursue your warranty claim directly with the manufacturer.

Your satisfaction is our #1 priority

If you're dissatisfied with your purchase, in any way, please contact us at - we will do our best to make it right.

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Gas Piston systems operate cleaner then the direct gas impingement operating systems. With the piston system, the propellant gases that are being diverted at the gas block are now vented at the gas block, instead in the operating system of the upper receiver. Since the fouling from the gas system is not being vented in to the action of your firearm, it stays cooler and cleaner. Our system is designed around the short stroke piston operation. The piston pushes the anti tilt one piece carrier, which unlocks the bolt and allows the piston to return home while the bolt carrier continues to cycle independently.

The upper is built off of CMMG's standard forged A3 receiver with M4 feed ramps. The chrome plated gas piston is mounted in a solid one piece steel gas block attached to the barrel by pins. The Gas Block's 1913 Picatinny rail is receiver height and requires a front sight designed to be mounted on the same plane as the rear sight. The dedicated, piston specific, anti-tilt bolt carrier is one piece, machined with the piston impingement key(not a bolt on). The carrier uses our standard Mil-Spec bolt. The barrel is our 4140 steel, M4 profile, 5.56mm chamber and bore, 1:9 twist ratio and 1/2x28 threaded barrel and our proprietary WASP surface treatment. The upper is finished with M4 handguard caps, M4 handguards and an A2 flash hider installed with a crush washer.

The piston gas block has a gas shut off setting for use with a suppressor to allow for maximum noise reduction. You must replace the crush washer with a peel washer if you plan to mount your suppressor on the original flash hider. Fits on any standard Mil-Spec lower receiver. All uppers have been factory head spaced and test fired. There are no upgrade options available with this model. Nickel bolt carriers are discontinued and now come with a phosphated carrier.

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