Now shooters can replace their AR Trigger with one that is smooth and breaks crisp. he trigger is factory preset with a pull weight of 4 lbs. Installation is quick and no adjustments are necessary, 100 percent true drop-in trigger. The trigger module installs using your rifle's original hammer/trigger pins and the proprietary design eliminates pin rotation and walkout. IF YOU HAVE A POLYMER LOWER, Timney recommends putting a small thin piece of aluminum underneath the trigger to protect the polymer lower.