Key Measurement
The bolt carrier’s tail must measure approximately 2.17"–2.2" for the lever to move correctly.
Installation Instructions
Assemble the Lever:
Use a 5/64" Allen wrench to attach the included machine screw and lock washer to the lever.
Apply Loctite or thread locker to prevent the screw from loosening.
Thread the included spring onto the screw until it’s snug against the lever.
Spring Adjustment for Receiver Type:
PSA/DPMS Lowers: These require a shorter lifter spring. If the spring deforms after manually cycling the action, cut off 2–3 coils with sharp wire cutters and recheck for deformation.
Aero M5/Stag10 Lowers: The included spring should work without cutting unless it deforms during use.
Note: Removing or replacing the spring may damage it unless you unscrew the machine screw from the lever.
Install the Push Button Safety:
Insert the safety from left to right, with the keyhole slot facing up and entering the receiver first.
Position the safety flush against the left interior wall of the receiver, then place the lever in front of the safety, with the lever’s "tail" pointing toward the buffer tube. (Installing it backward will cause issues.)
Push the safety until it lightly touches the lever, then twist to align the keyhole slot with the lever. Press the safety fully through the receiver.
Install the Detent:
While pressing the safety, flip the receiver upside down so the safety detent hole faces up.
Insert the included detent (rounded end first) into the hole.
Twist or pull the safety to position the detent correctly in its slot.
Install the Grip:
Place the safety detent spring inside the grip, then attach the grip to the receiver.
Tighten the grip screw until it stops.
Test the safety: It should move smoothly between Fire (all the way right), Safe (all the way left), and Active Safety (middle) with enough resistance to prevent accidental movement.
Important: Do not shorten or cut the safety selector spring.
Fitment and Modifications
Upper Receiver Modification:
To allow full lever movement, extend the slot/opening in the upper receiver to the rear takedown lug using a Dremel (be careful!).
The cut should be flush with the rear takedown lug.
Lever Adjustment:
If the bolt binds when cycling the action, the lever may be too tall and needs slight sanding.
The lever must fit between the upper receiver and the bottom of the bolt carrier when fully retracted.
With the rifle unloaded and in Safe mode, cycle the bolt by hand. If it binds:
Tap the muzzle downward firmly to free the bolt, or remove the upper with the bolt partially retracted.
Check for scrape marks on the lever to identify contact points.
Lightly sand the top of the lever with 80–120 grit sandpaper (remove about the thickness of a human hair). Repeat if needed.
High Shelf Lower Receivers:
Some lower receivers have a “high shelf” behind the safety selector hole, which can block the lever’s movement and cause binding or damage.
Check for High Shelf: Place a 1/8” gauge (like a drill bit or Allen wrench) across the top of the lower receiver. The lever should rest freely on the gauge on both sides, not just the center.
Solution: If the shelf is too high, use a Dremel with a carbide cutter to remove material directly behind the safety selector hole to allow free lever movement.
Why It Matters: If the rifle is laid on its side (e.g., on a shooting bench), the lever may shift and get obstructed by the shelf, causing bolt binding, lever damage, or unintended safety position changes.
Troubleshooting Tips
If the bolt binds or the safety doesn’t function smoothly, double-check the lever orientation, spring length, and receiver modifications.
Ensure the lever moves freely and isn’t obstructed by the receiver shelf or bolt carrier.