HK MP5 .22LR INSTALL/TROUBLESHOOTING HOW-TO

Robert Wells   Apr 30, 2026

FRT Install Troubleshooting HowTo

HK MP5 .22LR Installation/Troubleshooting Guide

 

Remove the trigger housing unit from your firearm and remove the cover from the unit.

 

 

 

 

 

 

 

 

 

 

 

Remove loose internals and hammer.

 

 

 

 

 

 

 

 

 

 

 

 

Remove both springs from the unit and remove the trigger assembly.

 

 

 

 

 

 

 

 

Remove this pin and spring. Your FRT will replace this spring in the reverse assembly.

 

 

 

 

 

 

 

 

 

 

 

This is the correct orientation of the FRT. It should be a reasonably tight friction fit and some light sanding may be helpful.

 

 

 

 

 

 

 

 

 

 

 

Reverse install starting with the springs.

 

 

 

 

 

 

 

 

 

 

 

 

Complete reassembly and close the housing.

 

 

 

 

 

 

 

 

 

Common Issues

 

If you are experiencing out of battery detonations at an abnormal rate, your bolt speed is likely needing adjustment. Per the HK manual, use these recommendations to fine tune your firearm.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

• If the trip falls forward into the firearm, it will stop functioning and jam the gun. The friction fit, and the improved geometry of the Gen 3 FRT SHOULD prevent this from happening, but manufacturing tolerances may allow for clearances our test guns did not have. if this happens the FRT will continue to function if rolled back into position, however point the gun down may cause the issue again.

 

 

 

• REMOVE YOUR EXTRACTOR BEFORE USE – The MP5 is a blowback operated firearm and does not need the extractor to function. If the extractor is not removed, an OBD may remove it for you. It has been known to happen in this platform, even in semi automatic fire.

 

         You will need to be careful and mindful to remove the round from the chamber, should you stop shooting before and empty magazine.