AR-15 FRT HOW-TO & TROUBLESHOOTING

First Employee   Feb 28, 2026

AR-15 DROP-IN FRT HOW-TO

The AR-15 Drop-in FRT is designed to fit in “MOST” mil-spec rifles, however many manufacturers have made design changes.

Two housings are included in the kit and correct installation of each is as shown:

 

The large housing fills the cavity around the hammer and sits flush with the receiver. Always insert and remove in a straight motion to avoid damaging the ears of the body. The lever of the trip lays against the hammer when closing the receiver.

 

 

 

 

 

 

 

The small housing sits directly above the safety with the lugs in the curves of the hammer pocket. The lever of the trip lays against the hammer when closing the receiver.

 

 

 

 

 

 

 

 

If something does not feel right, or looks incorrect, STOP. DO NOT FORCE IT, you may break the housing.

 

To determine which housing is ideal for your rifle, or if the trip is compatible with your setup there are a few things to consider:

 

 

 

 

 

 

 

 

 

 

 

The small body REQUIRES your upper to be relieved with the “oval” shape. If your upper receiver does not have this feature, it will crush the housing.

 

If your lower receiver has a “High Shelf” (the shelf is even with or over the top of the safety selector) you may encounter a few fitment issues. This is due to the rear of the trip hitting the shelf. You may experience the bolt not being able to cycle or silver marks appearing at the impact points.

 

 

 

 

 

 

 

A possible resolution is minor shaping of the rear of the trip. This can resolve the “square peg, round hole” issue.

 

 

 

 

 

 

 

 

Take your time, go slow, test fit, and DO NOT FORCE ANYTHING.

 

 

 

 

 

 

 

 

 

We have noticed some incompatibilities with some receivers. If the pocket of your receiver is asymmetrical, you may experience some wobble causing failures to reset. If this is the case, we may have designs already in place that work for you, please feel free to ask.

 

If your receiver shelf does not have much space behind the safety selector, the trip may not fully seat causing the failures illustrated above. This incompatibility is usually not able to be addressed with the above solution.

This receiver has minimal space between the shelf and the safety selector and was incompatible with the trip without permanant modification to your receiver.

 

 

 

 

 

This receiver shown earlier with the high shelf, has enough room for the modifications to solve the issue.

 

 

 

 

 

 

 

 

If you are unsure, STOP. Reach out to us, we will try our best to assist you.