FRT-RD3™ (SEF)

About this product

The FRT-RD3™ (SEF) is a two-stage, three-position forced reset trigger specifically engineered for HK MP5, MP5K, SP5, and SP5K platforms requiring an SEF grip frame. This drop-in system replaces the factory fire control group, utilizing a proprietary geometric lock and a 4140 steel hammer to mechanically force the trigger forward after each shot, eliminating the need for manual trigger reset. Its 3-position selector (Safe, Semi, Forced Reset) provides distinct firing modes, with the forced reset function activated by a dedicated lever arm that engages the bolt carrier during cycling to achieve consistent reset timing within a 0.5-1.0 ms window post-bolt lock.

What is the FRT-RD3™ (SEF) used for?

The FRT-RD3 is used for converting an HK MP5-pattern firearm with an SEF grip frame into a forced-reset firing platform. Its primary mechanical function is to eliminate user-induced reset lag by using bolt carrier energy to positively return the trigger to the forward, ready position. This is engineered for rapid, controlled pairs and strings where consistent reset timing is critical, though it does not alter the firearm's rate of fire beyond the operator's mechanical capability to follow the forced forward motion.

How does the FRT-RD3 compare to the Franklin Armory BFSIII HK-C1 binary trigger?

The FRT-RD3 is mechanically superior for achieving a consistent, positive reset, whereas the Franklin Armory BFSIII HK-C1 operates on a traditional binary 'pull-for-shot, release-for-shot' principle. The forced-reset action of the FRT-RD3 provides a tactile, forward push of approximately 0.080 inches of travel, resulting in a more predictable trigger rhythm for advanced dynamic shooting. The Franklin Armory system, while functional, relies on the shooter to fully release the trigger to its reset point, introducing greater potential for timing variance under high-speed manipulation.

What does it weigh and what are the dimensions?

The complete FRT-RD3 trigger assembly weighs 84 grams, with the hammer component accounting for 22 grams of that total. Its critical packaged dimensions are 2.12 inches in length, 1.03 inches in width, and 0.55 inches in height, designed to be a direct drop-in replacement for the OEM MP5 trigger housing. The included SEF safety selector adds an additional 18 grams and is 1.85 inches in length, with a detent spring requiring a pre-load force of 1.2 lb-in.

Who is this NOT for?

This trigger is not for owners of MP5 clones with ambidextrous or Navy-style grip frames, as the housing geometry and safety selector are incompatible. It is also not for shooters seeking a lighter break weight; the forced-reset mechanism maintains a consistent 8.5-lb first-stage pull and a 5.2-lb second-stage break for reliability. Finally, it is not suitable for jurisdictions where forced-reset triggers are restricted by local interpretation; consult our state-by-state technical analysis before purchase.

What's in the box?

The box contains one (1) FRT-RD3 forced reset trigger assembly, one (1) SEF single-sided safety selector, one (1) 1/16-inch Allen key for selector installation, and one (1) 3/32-inch Allen key for potential housing pin adjustment. No spare springs or shims are included, as the system is pre-timed at the factory to a tolerance of +/- 0.002 inches on the hammer/sear engagement surfaces. This contrasts with more generic drop-in kits that include multiple components, such as those mentioned in our guide on Glock G19 Gen6 reliability.

Is the FRT-RD3 worth it at $615?

At $615, the FRT-RD3 is worth the cost for a dedicated HK platform shooter who values mechanical reset precision over a traditional binary function. The investment is justified by the specialized machining of the 4140 steel hammer and the proprietary sear geometry, which provide a measurable increase in reset consistency—a critical factor not addressed by standard aftermarket triggers. For general recreational use, a traditional semi-auto trigger at a lower price point may suffice.