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U.S. Arms Cam-Lock Lower Receiver


The USAC M-4 CLS Cam-Lock UTAW Lower Receiver improves the accuracy of any AR-type firearm.
This is a stripped lower receiver. Includes trigger guard.

ATF regulated items have restrictions and requirements:

  • Your order will ship only to a Federal Firearms License holder.
  • We are not currently shipping to CA, CT, DC, HI, MD, MA, MN, NJ, NY, or VA.
  • Please be sure to contact your local FFL dealer prior to placing your order to ensure they are still accepting transfers. Some FFL dealers are not open due to Covid-19.
  • Customer must read, understand, and agree to customer terms and conditions.









8.25 oz

U.S. Arms has developed a revolutionary new device that improves barrel stability and accuracy through a secure fit, bringing the upper and lower receivers into proper alignment. This improves the accuracy of any AR-type firearm by securely transmitting torque through the lower receiver into the shooter’s shoulder and wrist.

High-speed video shows forward movement of an AR upper receiver and then a rolling motion induced by the bullet/barrel interface torque. This technology completely removes upper/lower loose fit by pulling rearward, preloading the front pivot pin, and pulling back and down on the rear take-down pin, which securely mates the upper receiver into the lower receiver bed.

This system allows the shooter to have the equivalent of a bolted together upper and lower receiver group while maintaining the ability to quickly and effectively disassemble the firearm in a traditional manner through a simple thumb lever attached to a cam shaft.

Testing reveals up to half an inch of Minute of Angle improvement with certain upper receivers when attached to the USAC Cam-Lock Lower Receiver. You will not find a tighter receiver on the market.

Compatible with all Mil-Spec upper receiver groups, both piston and gas impingement systems for:

  • AR-15
  • M-16 A1A2