Installing a bolt catch


If you have any doubts in your ability to perform the following actions, stop immediately and seek assistance from a qualified gunsmith. If you need clarification on any of the steps below, please contact us to speak with a member of our support team.

Always wear proper personal protective equipment (PPE) including adequate eye protection when servicing a firearm.

Parts needed:

  • Angstadt Arms 0940 or 1045 lower receiver
  • Standard mil-spec bolt catch
  • Standard mil-spec bolt catch plunger
  • Angstadt Arms lightened bolt catch spring
  • Angstadt Arms bolt catch dowel pin
  • Angstadt Arms bolt catch set screw
  • 1/16″ hex end wrench
1. Insert bolt catch plunger into lower receiver

Attach the lightened spring to the AR-15 bolt catch plunger. With the spring attached, drop the plunger into the hole on the left side of the lower receiver. VERY IMPORTANT: Do not use a standard AR-15 bolt catch spring.

2. Attach bolt catch to actuator
Place the bolt catch into the cut in the receiver and attach the front of the bolt catch to the hole in the bolt catch actuator.

3. Insert dowel pin
Place the dowel pin into the threaded hole and insert fully.

4. Install set screw
Gently thread the set screw into the the hole using a 1/16″ hex end wrench. VERY IMPORTANT: Do not force the screw into the hole. If you meet any resistance stop and back the screw out of the hole. Ensure the screw is properly aligned before inserting again.

5. Check proper function
Fully insert an empty magazine into the magwell and confirm the bolt catch is fully depressed. IMPORTANT: Place the upper receiver onto the lower receiver when testing proper function as the upper receiver limits the travel of the actuator. In the image below the upper received has been removed for illustration purposes.