Reinstalling bolt catch actuator/transfer bar


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 0940/1045 lower receiver or complete UDP-9/UDP-45 firearm
  • Angstadt Arms 0940/1045 bolt catch actuator
  • 3/32″ punch

1. Completely remove upper receiver

2. Remove existing actuator
Insert a 3/32″ punch from the left of the lower receiver and drive the 5 /16″ roll pin into and out of the receiver.

3. Install roll pin
Insert the 5/16″ roll pin into the hole on the left of the lower receiver. Drive the pin until it slightly protrudes past the opening, do not fully install the roll pin at this time.

4. Install new actuator
Inserting the rear opening of the actuator over the bolt catch and slide the front of the actuator over the roll pin you just installed. Finish installing the 5/16" roll pin. VERY IMPORTANT: The roll pin must span both sides of the actuator.

5. Check proper function
Test to ensure the actuator is functioning properly.