This is the MLOK model, 8100579, which was upgraded in 2021 from the older handguard variant.
The MR556A1 uses the HK proprietary gas piston operating system, employing a piston and a solid operating ‘pusher’ rod in place of the gas tube normally found in certain firearms. This method of operation virtually eliminates malfunctions that are common to direct impingement gas systems since hot carbon fouling and waste gases do not enter the receiver area. This is the same key feature critical to the success of the HK416 rifles used by leading military and law enforcement customers.
The MR556A1 is produced in the USA using American and German made components. The MR556A1 uses many of the same assemblies and accessories originally developed for the HK416.
For those of you who follow imported rifles, civilians cannot own a semi-automatic rifle made in Germany, or made of 100% German parts. As much as HK fans would like that, there is an unusual, and to many, somewhat obscure gun law, known as Section 922(r). Title 18, USC Section 922(r) makes it unlawful to import or construct or assemble from imported parts, a semi-automatic military style weapon. The regulations that implement Section 922(r) provide a list of rifle parts, and basically, for you and me to own a German semi-automatic rifle, many of the parts need to be made in the USA. This is why we cannot buy a pure H&K 416, and which is also why H&K is now doing the final assembly of the civilian version of the 416 - this MR556A1, in the US. It is a bit of an odd law, but it has its roots in restricting the importation of Chinese and Soviet surplus rifles. Between extreme restrictions in US law, there are also very stringent German laws regarding what can be exported.
The MR556A1 also has a Picantinny rail machined into the top of its upper receiver for mounting optics and mechanical sights. Unlike earlier prototypes, major subassemblies, including the MR556A1 upper receiver/barrel assembly, are fully interchangeable with other high quality AR-style firearms. MR556A1 upper receiver kits can be used to retrofit competing legacy AR systems.
Like the famous HK416, the MR556A1 uses a German-made barrel produced by Heckler & Koch’s famous cold hammer forging process. The highest quality steel is used in this unique manufacturing process producing a barrel that provides superior accuracy and long service life. But unlike the HK416, the MR556A1 does not use a chrome-lined barrel. Chrome-lining can sometimes mask bore imperfections and negatively affect accuracy. For the new series of Heckler & Koch semi-automatic MR rifles, HK designers and engineers believe best accuracy comes with an unlined bore. Used with the HK Free Floating Rail System, the barrel does not touch the handguard, ensuring the barrel is truly free-floating for maximum accuracy. The unchromed barrel has an internal profile of 6 lands and grooves with a 1 in 7 inch (178 mm) twist. It is also moderately ‘swagged’ with a slightly smaller internal diameter at the muzzle end than the chamber end. This feature has a positive effect on bullet accuracy and velocity. The thick, heavy contour 16.5-inch MR556A1 barrel also contributes to its excellent accuracy.
A precise enhanced two-stage trigger adds significantly to the accuracy of the MR556A1 and an extended latch charging handle makes operating the rifle with a telescopic sight easier. The retractable buttstock can be locked into a solid, non-moving position by tightening an Allen screw in the bottom of the stock. Special target rifle takedown pins ensure the upper and lower receivers are firmly mated for accurate performance.
Designed to function with a wide variety of high quality 5.56 x 45 mm ammunition, the MR556A1 uses a C.I.P. dimensioned chamber (a chamber with dimensions specified by the Commission Internationale Permanente).The MR556A1 also functions reliably with most quality Caliber .223 Remington ammunition.
| Caliber: | 5.56mm |
| Weight: | 9.10 lbs. |
| Rifle Overall Length: | 33.9" - 37.68" |
| Action: | Semi-automatic |
| Trigger: | 7.64 lbs |
| Safety: | Ambidextrous selector lever |
| Rifle Barrel Length: | 16.50" |
| Rifle Barrel Twist: | 1:7" |
| Rifle Stock: | Reinforced carbon-fiber polymer |
| Scope Mount: | Free floating rail |
| Handedness | Right Hand |
| Item Condition | New |
| UPC | 642230262553 |
| MPN | MR556-A1 / 81000579 |
Buying and shipping through Charlie’s is easy, but there is some information you need to know. This item must ship to FFL holder. No civilian exceptions.
1) Check your state laws to make sure the federally regulated item you want to purchase is legal in your state.
2) Find your FFL… Have your dealer send us a copy of their FFL to Charlie’s (Make them earn their fee!!!)
3) Be patient! You should hear from our compliance department within 3-4 business days. If not, feel free to reach out for a status update.
That’s it! We try to make this process as simple as possible for our customers. Please click the “Buying a Firearm” tab at the top of this page for more information.
California residents please, click here. California Residents will pay the discounted price for the rifle, but will receive the upper and lower separately
NOTE: The free shipping option does not apply to full rifles
THIS IS A SERIALIZED FIREARM. It must ship to a Federal Firearms License holder. No civilian exceptions.
Buying and shipping through Charlie’s is easy, but there is some information you need to know. Only a federally licensed firearms dealer may receive a firearm or federally regulated serialized item (like a receiver or suppressor). We cannot ship these items directly to you. Please follow these steps to process your transaction:
1) Check your state laws to make sure the federally regulated item you want to purchase is legal in your state. Your FFL dealer should be able to give you all of the necessary information regarding your state specific laws. But, if we ship to your FFL, and there is a legal issue, we cannot accept a return. So please make sure that you know and follow your local and state laws.
2) A quick google search will show you what Federal Firearms Licensed (FFL) dealers are in your area. When you are ready to purchase, contact the FFL dealer you would like to use and get their shipping address. During the check-out, put YOUR address in the “billing” section and the FFL DEALER’S address in the “shipping” section. If you don’t know your FFLs address, that’s okay. You can send the information later.
3) After check out, make sure to contact your FFL dealer to ensure they will receive your shipment for you (most do this for a small fee, but you should always double check).
4) Have your dealer send us a copy of their FFL to FFL@CharliesCustomClones.com. Charlie’s does not reach to your FFL (MAKE THEM EARN THEIR FEE!!!)
5) Be patient! In order to ensure we remain compliant with all federal laws, our compliance department is kept separate from our sales and operations team. Please allow a few days for our compliance officer to verify all of your dealer’s documents and ensure all federal laws are being observed. You should hear from our compliance department within 3-4 business days. If not, feel free to reach out for a status update.
That’s it! We try to make this process as simple as possible for our customers, but if you are unfamiliar the process or have any other questions, please visit our How to Buy a Firearm page for more details.
California and New York residents please, click here. The process may be different due to state specific laws.
NOTE: The free shipping option does not apply to full rifles, unless purchased with a riflescope. If you choose free shipping at check-out, we will bill you for shipping later.
Heckler Koch
