HK & MP5 FRT Triggers

Choosing an MP5 FRT

There are two ways to add a forced reset trigger to an HK roller-delayed firearm, and the right one depends on your model.

Option 1: a complete FRT lower

MARS lowers come with the fire control group and a 3-position super safety already installed in a polymer grip frame. You swap your factory lower for the MARS unit, with no trigger pack to build. Each lower is made for one host firearm: HK SP5 and SP5K, Zenith ZF-5 and ZF-5K, PTR 9, MAC 5 and MAC 5K, and MKE AP5 and AP5-P. Order the one that matches your exact model.

Option 2: a drop-in MP5 FRT trigger

The Rare Breed FRT-RD3 is a two-stage forced reset trigger built for HK MP5, MP5K, SP5 and SP5K pattern firearms. It works with the factory semi-auto bolt carrier. It comes in two versions, so check your grip frame first: AMBI frames have pictogram markings and levers on both sides, and SEF frames have S-E-F letter markings.

HK MR223 and MR556

The Rare Breed FRT-MR3 is made for the HK MR223 and MR556 and runs with the factory semi-auto carrier, buffer and spring. It comes with a curved or flat shoe.