Brownells Gun Tech™ Caleb Savant shows us how to install an Elftmann ELF Pro-Lock AR-15 trigger. These triggers are available as self-contained drop-in trigger modules or as component triggers, both with a twist. Instead of traditional pins, they are retained by screws that thread into the sealed hammer and trigger bearings. The "Factory Method" of installation employs a flat washer AND a split washer under the screw head on the outside of the receiver. This is a bit bulkier than Caleb likes, so he foregoes the split washer and retains the screw by applying a little blue Loctite® thread-locker. He also puts some blue Loctite® on the screws on the underside of the trigger module before he drops it into the lower. Then he snugs up all the screws for a very secure, tight installation that actually stiffens up the entire lower receiver. Drop the hammer to the half-cock position (yes, Elftmann AR-15 triggers have one!) and install the safety selector, its detent, and the pistol grip. Then function check the trigger and safety. The result is a super-smooth trigger with a "glass rod crisp" break and a super-short reset. Feeling triggered to install an Elftmann ELF Pro-Lock trigger in your AR-15? We hope so!