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.
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On Sale
HK MP5 Receiver Flat with Weldment Set
PTR
Now: $265.45Was: $294.95MP5 9mm Receiver Flat With Complete Weldment & Rivet Set - PTR/LSC Several years ago PTR bought out LSC and now owns the tooling and dyes for the LSC 9mm flats. These elusive flats have been hard to find and are now available for the first time here...Now: $265.45Was: $294.95 -
On Sale
HK416, HK417, MR556, MR762 Buffer Retaining Pin
H&K Heckler & Koch
Now: $14.36Was: $15.95H&K HK MR556/MR762/416/417 Buffer Retaining Pin New HK German proprietary HK designed buffer pin unique to the HK 416 and MR 556 series. Compatible With: HK MR556 HK 416 HK MR762 HK M27Now: $14.36Was: $15.95 -
On Sale
HK MP5, MP5K Cartridge Case Deflector, Shell Deflector - Billet
HKP HK Parts
Now: $15.96Was: $19.95Cartridge Case Deflector, Shell Deflector - MP5, MP5K - Billet New US made case deflector for receiver flat or receiver for all MP5, HK94, MP5K, & SP89 builds. The case deflector is riveted or welded in place on the ejection port of the 9mm receiver...Now: $15.96Was: $19.95 -
On Sale
HK MP5 Trunnion - 9mm
RCM
Now: $58.46Was: $64.95RCM MP5 9mm Trunnion US made to exact factory HK specifications and machined completely from ordnance grade steel and heat treated to factory specs. Compatible With: MP5, 94 MP5K SP89 Clones or other custom buildsNow: $58.46Was: $64.95 -
On Sale
HK416, HK417, MR556, MR762 Takedown Pin Detent Spring
H&K Heckler & Koch
Now: $8.96Was: $9.95H&K HK MR556/MR762/416/417 Takedown Pin Detent Spring New HK German manufacture. Detent spring for the rear takedown pin. Compatible With: HK MR556 HK 416 HK MR762 HK 417Now: $8.96Was: $9.95 -
On Sale
HK MP5, MP5K Scope Tab - Weldment
HKP HK Parts
Now: $7.96Was: $9.95MP5, MP5K Sight Tab - Weldment HK MP5, MP5K 17-4 Stainless H900 rear sight tab. The most correct MP5, MP5K rear sight base available. If you want your build to look as factory correct as possible then this sight base is an absolute must. Compatible...Now: $7.96Was: $9.95 -
On Sale
HK416, MR556 Mil-Spec Enhanced Buffer Tube
H&K Heckler & Koch
Now: $229.45Was: $254.95HK 416 & MR556 OTB (over the beach) Buffer Tube/Receiver Extension Each mil-spec buffer tube has built-in drainage holes in the rear of the tube and also on the bottom to maximize efficiency. Each buffer tube has ball-bearing rollers to tighten the...Now: $229.45Was: $254.95 -
Out Of StockOn Sale
HK416 E1, MR556 Charging Handle - Ambidextrous
H&K Heckler & Koch
Now: $116.95Was: $129.95H&K HK MR556/416 E1 Charging Handle - Ambidextrous HK's design boasts a smooth & easy to release latch with an enhanced oversized charging handle. Compatible With: HK MR556 HK 416 Other AR15, M4 & M16 applicationsNow: $116.95Was: $129.95 -
On Sale
HK416, HK417, MR556, MR762 Takedown Pin - Rear - A1 Style
H&K Heckler & Koch
Now: $71.95Was: $79.95H&K HK MR556/MR762/416/417 Rear Lower Receiver Locking Pin This is the rear 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 lower receivers and improve...Now: $71.95Was: $79.95 -
Out Of StockOn Sale
HK91, G3, PTR Trunnion
RCM
Now: $58.46Was: $64.95RCM Trunnion For The HK91/G3 Series - US Made This part is machined from ordnance grade 9310 enhanced steel and heat treated to exact HK specifications. This item is the best USA-made trunnion on the market. Machined to spec and are to the custom ground...Now: $58.46Was: $64.95 -
On Sale
HK MP5, HK94 Case Deflector Rivet
H&K Heckler & Koch
Now: $8.96Was: $9.95H&K MP5, HK94 Case Deflector Rivet Each case deflector, US or German-made, will require two rivets to attach the case deflector to the receiver or flat. If you want the factory look and feel of doing it right, these rivets are a must-have. These are...Now: $8.96Was: $9.95 -
On Sale
AR15 Castle Nut for Buffer Tubes
Ergo
Now: $8.99Was: $9.99Ergo AR-15 Castle Nut For Buffer Tubes - US Made Steel Castle-nut for AR buffer tubes fits both mil-spec and commercial buffer tubes alike. Compatible With: HK MR556 & 416 AR-15 style platformsNow: $8.99Was: $9.99