CMMG Mk4T, 22LR Upper
CMMG .22Mk4: The Mk4 T Upper Group introduces CMMG's RKM series of KeyMod free float Hand guards. If you are purchasing this upper for use with the Echo Trigger, you will also need to purchase the Auto Sear Trip Kit. The Sear Trip Kit is required in order to engage the Trigger Lock and allow the trigger to be pulled. Don't forget to order a few .22 magazines! The .22 LR Uppers that are purchased from FosTecH will include an Extra Power Recoil Spring for customer installation.