Bring authentic HK folding-stock configuration to your compatible K-series firearm with the Heckler & Koch SP5K / MP5K Factory Folding Stock, part number 261249. Designed for the compact MP5K-pattern receiver, this black side-folding buttstock provides a traditional shoulder-stock configuration while retaining the compact storage advantages that make the K-series platform distinctive.
The MP5K was developed around a compact receiver and short overall profile. A fixed buttstock can compromise some of that compactness, while a folding stock offers a practical alternative. The HK folding design allows the buttstock to extend for shoulder-supported shooting and fold alongside the firearm when a shorter storage profile is preferred.
For owners building a properly registered SP5K or MP5K-pattern short-barreled rifle, choosing a factory HK accessory helps maintain the familiar appearance and intended fit of the original platform. Rather than adapting a stock intended for a full-size MP5 receiver, this model is specifically associated with the shorter K-series configuration.
The black polymer stock body complements the original HK styling and provides a durable, practical exterior. The right-side folding arrangement allows the stock to be stowed alongside the receiver for storage and transport.
This product is a firearm accessory and is not, by itself, an NFA-regulated firearm. Installing a shoulder stock on a pistol may result in a firearm classified as a short-barreled rifle (SBR).
Federal Regulatory Update – October 9, 2026: Following the federal court ruling in Silencer Shop Foundation v. ATF, ATF announced a nationwide policy of nonenforcement of NFA making, registration, and approval requirements for short-barreled rifles and certain other covered firearms. Under this policy, ATF does not require prior NFA Form 1 approval or registration before making a covered SBR.
This is an enforcement policy rather than a repeal of the NFA and may be subject to change. State and local laws remain applicable, as do relevant Gun Control Act requirements. Purchasers are responsible for ensuring their intended configuration is lawful in their jurisdiction.
For current federal guidance, see ATF's NFA Transfer Guidance.