Receivers / Flats / Uppers

Receivers / Flats / Uppers

Explore our premier selection of HK receivers, flats, and uppers at HKParts, perfect for building or upgrading your Heckler & Koch firearms. Our products feature precision-engineered MP5 receiver flats, HK 416 complete upper assemblies, and a wide range of custom options designed for tactical and precision shooting. Whether you are customizing an MP5, upgrading an HK416, or constructing a new firearm, our high-quality components provide unparalleled reliability and performance.

  • Product
  • Qty in Cart
  • Quantity
  • Price
  • Subtotal
  • On Sale
    New - H&K HK416 A5 Factory German Extended Castle Nut - HKP-19164
    Add to Cart

    HK416A5 Castle Nut - Extended

    H&K Heckler & Koch

    Now: $68.36
    Was: $75.95
    H&K HK416 A5 Factory German Extended Castle Nut Original HK Factory German steel 416 A5 Extended Castle Nut. Perfect for MR556, HK 416 A5 builds, or upgrades. 
    Now: $68.36
    Was: $75.95
    Add to Cart
    Qty in Cart: 0
    Quantity:
    Price:
    Now: $68.36
    Was: $75.95
    Subtotal:
    Add to Cart
  • On Sale
    New - H&K HK MR556/MR762/416/417 Detent Takedown Pin - HKP-02540
    Add to Cart

    HK416, HK417, MR556, MR762 Detent Takedown Pin

    H&K Heckler & Koch

    Now: $8.96
    Was: $9.95
    H&K HK MR556/MR762/416/417 Detent Takedown Pin Factory H&K takedown pin for MR556 A4. Compatible With: HK MR556 HK 416 HK MR762 HK 417
    Now: $8.96
    Was: $9.95
    Add to Cart
    Qty in Cart: 0
    Quantity:
    Price:
    Now: $8.96
    Was: $9.95
    Subtotal:
    Add to Cart
  • On Sale
    New - H&K HK MR556 Receiver Take Down Tool - HKP-02653
    Add to Cart

    HK MR556 Receiver Take Down Tool

    H&K Heckler & Koch

    Now: $17.95
    Was: $19.95
    H&K HK MR556 Receiver Take Down Tool This part is the tool used to tighten down the stock movement on the E1/E2 stock. Each tool will be stored in the rear of the E1/E2 stock. Compatible With: HK MR556 Please Note: We get...
    Now: $17.95
    Was: $19.95
    Add to Cart
    Qty in Cart: 0
    Quantity:
    Price:
    Now: $17.95
    Was: $19.95
    Subtotal:
    Add to Cart
  • On Sale
    New - MI HK MP5K 1913 End Plate Adapter - HKP-21584 HK MP5, MP5K Picatinny End Plate Adapter
    Add to Cart

    HK MP5, MP5K Picatinny End Plate Adapter

    MI Midwest Industries

    Now: $80.95
    Was: $89.95
    MI HK MP5K 1913 Picatinny End Plate Adapter The Midwest Industries Picatinny end plate adapter opens up a myriad of off-the-shelf stock and brace options. The adapter installs in the same manner as the factory end cap with a single push pin. Modification...
    Now: $80.95
    Was: $89.95
    Add to Cart
    Qty in Cart: 0
    Quantity:
    Price:
    Now: $80.95
    Was: $89.95
    Subtotal:
    Add to Cart
  • On Sale
    New - HK G36/SL8 (5.56/.223) Factory Recoil Buffer - HKP-18541
    Add to Cart

    HK G36, SL8 Recoil Buffer - Factory - US

    USA

    Now: $15.25
    Was: $16.95
    HK G36 Or SL8 Factory Recoil Buffer A must have spare part as the buffer is prone to wear and breakage. Compatible With: All HK G36 models SL8 models Clones
    Now: $15.25
    Was: $16.95
    Add to Cart
    Qty in Cart: 0
    Quantity:
    Price:
    Now: $15.25
    Was: $16.95
    Subtotal:
    Add to Cart
  • On Sale
    New - H&K HK MR556/416 Receiver End Plate - HKP-16603 HK416, MR556 Receiver End Plate
    Add to Cart

    HK416, MR556 Receiver End Plate

    H&K Heckler & Koch

    Now: $22.45
    Was: $24.95
    HK 416, MR556 End Plate For Receiver & Buffer Tube New HK German manufacture. Compatible With: HK MR556 & HK 416 upper receiver/buffer tubes
    Now: $22.45
    Was: $24.95
    Add to Cart
    Qty in Cart: 0
    Quantity:
    Price:
    Now: $22.45
    Was: $24.95
    Subtotal:
    Add to Cart
  • On Sale
    HK416, MR556 Buffer Tube Wrench HK416, MR556 Buffer Tube Wrench
    Add to Cart

    HK416, MR556 Buffer Tube Wrench

    HKP HK Parts

    Now: $23.96
    Was: $29.95
    HK MR556 & HK416 Buffer Tube Wrench The perfect metric wrench to remove and install the MR556 & HK 416 castle nuts on the buffer tube. A perfect addition to have on hand for OTB or other HK buffer tube upgrades, etc. Made from all steel, heat...
    Now: $23.96
    Was: $29.95
    Add to Cart
    Qty in Cart: 0
    Quantity:
    Price:
    Now: $23.96
    Was: $29.95
    Subtotal:
    Add to Cart
  • On Sale
    New - LSC/PTR Receiver Flat- MP5 9mm - HKP-01431 HK MP5 Receiver Flat- 9mm
    Add to Cart

    HK MP5 Receiver Flat- 9mm

    LSC

    Now: $215.95
    Was: $239.95
    MP5 Receiver Flat - PTR/LSC New PTR 9mm Receiver Flat made on the original LSC tooling. This flat is considered by many to be the most sought-after HK flat available on the market and perfect for that HK custom build. This item is not considered an FFL...
    Now: $215.95
    Was: $239.95
    Add to Cart
    Qty in Cart: 0
    Quantity:
    Price:
    Now: $215.95
    Was: $239.95
    Subtotal:
    Add to Cart
  • Out Of Stock
    On Sale
    New - H&K MP5 40/10 Case Deflector - HKP-02170 HK SP5 Case Deflector - 9mm / 10mm / .40 S&W

    HK SP5 Case Deflector - 9mm / 10mm / .40 S&W

    H&K Heckler & Koch

    Now: $44.96
    Was: $49.95
    SP5 Case Deflector - 9/10/40   Factory HK case deflector for the SP5 platform chambered in 9mm, 10mm, and .40 S&W.   Compatible With: H&K SP5 9/10/40  
    Now: $44.96
    Was: $49.95
    Out Of Stock
    Qty in Cart: 0
    Quantity:
    Price:
    Now: $44.96
    Was: $49.95
    Subtotal:
    Out Of Stock
  • On Sale
    New - H&K HK MR556 Front Lower Receiver Locking Pin - HKP-02663 HK416, MR556 Takedown Pin - Front - A1 Style
    Add to Cart

    HK416, MR556 Takedown Pin - Front - A1 Style

    H&K Heckler & Koch

    Now: $58.46
    Was: $64.95
    H&K HK MR556 Front Lower Receiver Locking Pin With Spring Loaded Detent This part is the front (large) takedown pin with ball detent and locking mechanism installed. The idea behind this type of system is to decrease the movement of the upper and...
    Now: $58.46
    Was: $64.95
    Add to Cart
    Qty in Cart: 0
    Quantity:
    Price:
    Now: $58.46
    Was: $64.95
    Subtotal:
    Add to Cart
  • On Sale
    New - HKP MP5 40/10 Receiver Flat - HKP-00767 HK MP5 40/10 Receiver Flat
    Add to Cart

    HK MP5 40/10 Receiver Flat

    HKP HK Parts

    Now: $146.21
    Was: $399.95
    MP5 40 & MP5 10mm Receiver Flat - USA The new and latest production with the weldment locations is already lasered and ready to go. This flat is the finest available for the MP5 40/10 family of firearms. Compatible With: MP5 .40 Cal MP5 10mm MP5 ...
    Now: $146.21
    Was: $399.95
    Add to Cart
    Qty in Cart: 0
    Quantity:
    Price:
    Now: $146.21
    Was: $399.95
    Subtotal:
    Add to Cart
  • Out Of Stock
    On Sale
    New - H&K HK MR556/416 Ejection Port Cover Door Assembly - HKP-16951 HK416, MR556 Ejection Port Cover Door Assembly

    HK416, MR556 Ejection Port Cover Door Assembly

    H&K Heckler & Koch

    Now: $80.95
    Was: $89.95
    HK German HK 416, MR556 Ejection Port Cover Door Assembly Complete This is the newer polymer style cover found on the latest HK 416 and MR556's. This is the complete ejection port door assembly needed on all AR15 or MR556/HK416 models. Can also be used...
    Now: $80.95
    Was: $89.95
    Out Of Stock
    Qty in Cart: 0
    Quantity:
    Price:
    Now: $80.95
    Was: $89.95
    Subtotal:
    Out Of Stock
  • Total: items /

Adding your products to cart

View Cart Continue Shopping