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 including the HK free-floating four-quadrant rail system. The HK Free Floating Rail System (FFRS) handguard has four MIL-STD-1913 ‘Picatinny’ rails and allows all current accessories, sights, lights, and aimers used on M4/M16-type arms to be fitted to the MR Series. The HK rail system can be installed and removed with simple tools and returns to zero when reinstalled.
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.
Weight: 9.10 lbs.
Rifle Overall Length: 33.9" - 37.68"
Trigger: 7.64 lbs Pull Weight
Safety: Ambidextrous selector lever
Rifle Barrel Length: 16.50"
Rifle Barrel Twist: 1:7"
Rifle Stock: Reinforced carbon-fiber polymer
Scope Mount: Picatinny Rail
Magazines Included: (1) 30 Round Magazine
Iron Sights Yes
Caliber or Gauge: 5.56 x 45mm NATO
Estimated shipping times are posted on the product information page under the title "Ships On Or Before:" please note that all lead-times are estimates. For items in our warehouse, we usually ship within 3 business days. For items only available at distribution or other sources, the ship time may be up to 10 business days. For items only available at the manufacturer, the lead-time may be a few weeks or longer-- depending on availability.
Please also note that some items are unique, hard to obtain, or one-of-a-kind, so Impact reserves the right to cancel your order should an item not be available to ship.
We will not charge your credit card until your product ships, except for certain special orders.
We normally will ship FedEx and US POSTAL. If you need faster shipment, we can ship 2nd Day or Next Day for an extra charge.
Alaska and Hawaii residents - your order MUST ship 2nd day or faster. Most orders over $100 value will ship with a signature-required to ensure they make it to you. Products that have free shipping only applies to the lower 48 states.
NOTE: We make every effort to get your order shipped as fast as possible. In some circumstances, especially during sales and after weekends, we may not get your order shipped in the time specified. Please rest assured that we will ship your item as soon as we can.
We want you to be 100% satisfied with your purchase from Impact Guns, therefore we offer no hassle returns.
How do I start the return process?
- Log in to your www.impactguns.com account and locate and click on the "Request Return" link.
- An Impact Guns agent will review your request for a return and respond within two business days.
- All returns are subject to inspection and approval prior to refund being issued.
- All products need to be in new and original manufacturer condition.
- As an alternate method, you can send an email to email@example.com. Please be sure to include your original order number and relevant contact information.
When will I get my credit or return?
- Most returns are fully refunded in 3-5 days after we receive and process the return. It may take longer for the credit to appear in your account depending on your bank. Most items that are in stock ship within 3-5 days after receipt of your returned item but may take longer depending on availability.
- Returns must be charged back to the original credit card used in the purchase. If this is not possible, we will refund you via check.
What about damaged/incorrect items?
- If you received a damaged, defective, or incorrect item, Impact Guns will ship you a replacement of the exact item upon receipt of the damaged or defective item. Impact Guns will send you a return shipping label for the return.
What about return shipping costs?
- If an Impact Guns error causes the need to return an item or we are replacing a returned defective or incorrect item, then we will pay the associated shipping costs.
- Otherwise, the customer is responsible for any return shipping costs. When returning an item, please add package tracking and adequate insurance.