FRT-RD3™ Forced Reset Trigger for the HK MP5, MP5K, SP5 & SP5K

$599.00

Contents:

1 x FRT-RD3 Trigger
1 x Ambidextrous/SEF Single-Sided Safety Selector
1 x 1/16 Allen Key
1 x 2mm Allen Key

Now Available!

Legal To Own And Purchase!

Prices are discounted until the end of: 11th August 2026

Buy this Trigger privately from us with no ATF transaction records! Pay securely using cryptocurrency (Bitcoin BTC or Ethereum ETH) or 3rd-party payment methods at checkout.

SKU: N/A Category: Rare Breed FRT Triggers

The FRT-RD3 is Rare Breed Triggers’ 3-position forced reset trigger built specifically for HK roller-delayed firearms — the HK MP5, MP5K, SP5 and SP5K. Part of the full Rare Breed FRT range, it resets after every shot for fast, controlled follow-ups while firing one round per trigger pull, and it is engineered from the ground up for the roller-delayed platform rather than adapted from an AR design.

Legality: one round per trigger pull. After the May 2025 DOJ settlement, forced reset triggers of this type are not classified as machine guns under federal law. State and local laws vary, so confirm yours before buying. You must be of legal age and eligible under federal, state, and local law to purchase.

Unlike AR-pattern FRTs, the FRT-RD3 works with the factory semi-automatic bolt carrier of the MP5/SP5 family. No full-auto carrier is required, and it is compatible with receivers that have factory full-auto carrier denial blocks with no modification to the firearm. As one of the most distinctive forced reset triggers we offer, it will also run with full-auto carriers if you have one, but you don’t need it, giving you simple, plug-and-play installation.

Specifications and fitment

Spec	Detail
Platform	HK MP5, MP5K, SP5, SP5K (roller-delayed)
Selector	3-position; AMBI or SEF single-sided (choose at checkout)
Pull	Two-stage, clean & crisp
Bolt carrier group	Factory semi-auto carrier (full-auto not required)
Modifications	None needed; works with factory denial blocks
Materials	7075 anodized aluminum, heat-treated 4140 steel
Manufacturer	Rare Breed Triggers

Choose AMBI or SEF

Pick the selector that matches your grip frame: a full ambidextrous (AMBI) selector or a single-sided SEF selector. The RD3 delivers a clean, crisp two-stage pull and is machined from 7075 anodized aluminum and heat-treated 4140 steel for duty-grade durability.

Frequently asked questions

Do I need a special bolt carrier? No. The FRT-RD3 runs on the factory semi-auto carrier of the MP5/SP5 platform, with no firearm modification needed. If you instead build on the AR-15, see the FRT-15C3.

AMBI or SEF, which do I pick? Match your grip frame: AMBI for ambidextrous (Navy/pictogram) frames, SEF for single-sided. Select your version at checkout.

Is it legal? Federally legal after the 2025 DOJ settlement (one round per pull); state laws vary.

Ready to upgrade your MP5? Add the FRT-RD3 to your cart above.