CMMG M4 LEP II Piston System Upper 16" 1/9 WASP 5.56/.223 10217

Looking for a dependable AR15 Piston system at the BEST price?  The CMMG complete upper is the "Best Bang for the Buck" affordable solution!

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. You may remove the piston and set the gas system to off for use with our .22 conversion system.

The upper is built off of our 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 dedicated, piston specific, anti-tilt bolt carrier is one piece, machined with the piston impingement key(not a bolt on) for maximum strength. The phosphated 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. Made in USA with a Limited Lifetime Warranty.

CMMG Barrel Specifications

    * Mil-spec certified 4150 chrome-moly vanadium steel barrel
    * 1/9 twist
    * WASP Protective Treatment
    * M4 feed ramps/Barrel Extension
    * 11 degree recessed target crown
    * 1/2x28 Threaded Muzzle
    * Parkerized Barrel, including under the front sight base
    * M4 contour

Each barrel is individually magnetic particle tested. Barrels are engraved CMMG WASP 5.56 NATO 1/9.

FAQ:

What is a WASP barrel?

W.A.S.P., or Weapon Armored Surface Protection, is simply a modern alternative to chrome lining. W.A.S.P. is a proprietary finish that provides the same durability and ruggedness as chrome lining, without the accuracy loss inherent in chrome lining. Additionally, W.A.S.P. not only protects the inside of the barrel, but the outside as well. Its matte black finish does not reflect. CMMG WA.S.P. corrosion resistance outperforms conventional chrome lining in salt water sea spray tests and provides, rugged reliability and durability essential to military grade firearms. 

With the growing popularity of the AR-15/M16 family of rifles the demand for ammunition has risen sharply. Unfortunately, this has made quality ammunition hard to find. CMMG recommends using only domestic, commercially manufactured ammunition or high quality surplus NATO specification ammunition.

Using any reloaded ammunition, any steel cased ammunition or Wolf Ammunition VOIDS your Limited Lifetime Warranty.

When purchasing domestically produced ammunition, questions can be answered by contacting the manufacturer directly. They will have the most accurate information about their products. If you have a problem with any ammunition be sure to have the lot number from the packaging that the ammunition in question came from; the manufacturer will need this information.

When purchasing surplus ammunition, it is not likely that the manufacturer is known or can be contacted. Most surplus ammunition is not from questionable sources, but some surplus ammunition is from rejected lots that did not meet a required specification. Find out as much as you can or purchase a small sample of the surplus ammunition before purchasing larger quantities. AR-15.com has the Ammo Oracle, and can answer most questions on ammunition. Many message boards will also have posts with reviews on ammunition by members. While these resources do not represent the final authority in ammunition related issues, they serve as a helpful guide for general information concerning various types of ammunition.

Before Firing Any Ammunition, inspect each cartridge for defects. Dispose of cartridges that exhibit and of the following defects:

    * Deformed brass, which includes burrs, cracks, dents, scratches, bent or bowed cases.
    * Deformed bullet, which includes burrs, dents and scratches.
    * Improperly seated bullets. The case neck should be uniform with no deformations and the bullet should be seated tightly in the case. Check overall length to ensure the bullet is not seated too deeply or has been pushed in from an impact. Some ammunition may have a colored sealant around the case neck.
    * Improperly seated primers. The primer should be flush with the base of the case with no visible damage to the primer cup. Some ammunition may have a colored sealant around the primer.
    * Corroded cartridges with any amount of metal that is corroded and eaten away.
    * Do not fire cartridges exposed to extreme heat (135 degrees F) until they have cooled.



Warning Signs
Not all defective ammunition has visible traits to distinguish it from good ammunition. If any cartridge from a lot of ammunition exhibits any of the following characteristics, discontinue the use of the entire lot and contact the manufacturer or dispose of the ammunition properly.

    * Inconsistent function. This can also be a firearm related malfunction. Clean and test the rifle with another source of ammunition. If proper function is restored discontinue the use of the suspect ammunition immediately.
    * Blown primers. This is an indication of improper powder charge. Discontinue the use of the suspect ammunition immediately.
    * Inconsistent sound. Noticeably louder or quieter reports indicate improper powder charge. Discontinue the use of the suspect ammunition immediately.
    * Cartridge fails to chamber. This can also be a firearm related malfunction. Clean and test the rifle with another source of ammunition. If proper function is restored discontinue the use of the suspect ammunition immediately.


Other ammunition related problems can occur. If you believe that ammunition you are using is preforming in an inconsistent manner, do not take any chances that you are experiencing a one-off occurrence. Discontinue the use of the suspect ammunition and contact the manufacturer.

Your rifle is a sizable investment. Make every effort to use quality ammunition, to ensure your safety and and prolong the life of your firearm for years of enjoyment.