Heckler & Koch HK417

The HK417 is similar in internal design to the HK416, although the receiver and working parts are enlarged to suit the larger 7.62×51mm cartridge. The bolt is a seven-lug rotating type, which sits in a bolt carrier and operates in a forged alloy receiver resembling those of the Stoner-designed AR-10, AR-15 and M16 rifles.

Like the HK416, the HK417 is gas-operated with a short-stroke piston design similar to that of the Heckler & Koch G36. The short-stroke piston may be more reliable than the original direct impingement operation of the AR-15 design because, unlike these weapons, it does not vent propellant gases directly into the receiver, which deposits carbon fouling onto the bolt mechanism as well as heating it up.

The early HK417 prototype used 20-round magazines from the Heckler & Koch G3 rifle family, which did not feature a bolt hold-open device. Later prototypes, however, switched to a polymer magazine with bolt hold-open. The magazine resembles an enlarged version of the G36's transparent magazine, except without the pins for holding more than one magazine together.

Purchasers of the HK417 have typically intended it to complement lighter assault rifles chambered for less powerful intermediate cartridges (often 5.56×45mm NATO), for the designated marksman role. The HK417's greater accuracy, effective range, and penetration offset its greater expense, its lower rate of fire, and its smaller ammunition capacity both in magazine and carriage.

Military and law enforcement

The HK417 models chambered for 7.62×51mm NATO available to the military and law enforcement market are:

• HK417 12″ 'Assaulter': carbine with 304.8 mm (12 in) standard barrel
• HK417 16″ 'Recce': "Recon" rifle with 406.4 mm (16 in) standard or accurized barrel
• HK417 20″ 'Sniper': "full size" rifle with 508.0 mm (20 in) accurized barrel

Improved model

The HK417A2 is an improved version. The design of the receiver, barrel interface, gas port and the bore axis alignment of the rifle have been further optimised to increase its accuracy and reliability. The German Army uses the HK417 A2 - 13″ with the designation G27.

As of 2013, the HK417A2 models chambered for 7.62×51mm NATO available to the military and law enforcement market are:

• HK417A2 - 13″: carbine with 330.2 mm (13 in) barrel
• HK417A2 - 16.5″: rifle with 419.1 mm (16.5 in) barrel
• HK417A2 - 20″: "full size" rifle with 508.0 mm (20 in) barrel

A barrel can be changed in under two minutes with simple tools. All HK417 barrels are cold hammer forged and chrome-lined and use a conventional lands and grooves bore profile with a twist rate of 1 turn in 279.4 mm (11.00 in). They are designed to function reliably with bullet weights ranging from 9.3 to 11.34 g (144 to 175 gr) and are threaded for a flash hider or sound suppressor. Optional accurized barrels with a different chrome treatment can provide up to 0.3 mil (1 moa) accuracy (with match grade ammunition).

G28

After using the HK417 as a stopgap designated marksman rifle under the G27 designation, the civilian MR308 was used to develop the G28, a designated marksman rifle for the German Bundeswehr (Federal Army) deployment to the War in Afghanistan. The semi-automatic G28 is chambered for 7.62×51mm NATO and has a factory warrantied accuracy of 45 mm dispersion at 100 meters (0.45 mil or 1.5 moa) when fired with 10 rounds using OTM/HPBT/Sierra Match King ammunition. The G28 features STANAG 4694 NATO Accessory Rails that are backwards-compatible with the STANAG 2324/MIL-STD-1913 Picatinny rails. The upper receiver is made from steel instead of HK's aluminium alloy. Approximately 75% of the parts are interchangeable with the HK417. There are two different versions of the G28: G28 E2 (Standard) with a Schmidt & Bender 3-20×50 PM II (modified to Bundeswehr requirements) and the G28 E3 (Patrol) with Schmidt & Bender 1-8×24 PM II. By October 2017, Heckler & Koch had renamed the G28 as the HK241, though G28 remains its Bundeswehr designation.

M110A1

The M110A1 CSASS is the U.S. Army's type designation for the Compact Semi-Automatic Sniper System. In April 2016, Heckler & Koch confirmed that a lighter version of the G28 had won the United States Army's CSASS contract to replace the M110 Semi-Automatic Sniper System. The M110A1 uses an aluminum upper receiver instead of steel to meet weight requirements, weighing 8.4 lb (3.8 kg) unloaded and reaching some 15 lb (6.8 kg) loaded and with accessories; the M110A1 features a Geissele M-LOK rail handguard, Schmidt & Bender 3-20×50 PM II Ultra Short telescopic sight, Geissele optic mount, OSS SRM6 suppressor, 6-9 Harris bipod and mount, and a collapsible stock with adjustable comb. In May 2018, the U.S. Marine Corps will begin receiving the CSASS, also to replace the M110. There has been some small-scale testing of the CSASS since then but no news of widespread fielding or adoption. However, the Army has shown small scale testing and use of the M110A2, an upgraded version of Knight's Armament Company's M110 SASS. The Navy and Marine Corps have also designated funding for a M110 SASS Product Improvement Program (PIP).

The M110A1 SDMR is a Squad Designated Marksman Rifle (SDMR) being issued to US Army infantry squads to replace the M14 EBR. In March 2018, the Army announced that a version of the G28E-110 would be issued to infantry squads as the service's standard SDMR. While undergoing evaluation by PEO Soldier, it was designated as M110E1. Issuing a 7.62×51mm NATO SDMR is meant to increase individual squads' ability to engage distant threats and defeat enemy body armor that standard 5.56×45mm NATO rounds cannot penetrate. The M14 EBR was previously issued for this role, but because it was based on an operational needs statement they had to be turned in by units at the end of a combat deployment. Unlike the sniper configuration, the SDMR model will be equipped with a different buttstock and barrel twist than the CSASS model. The SDMR model will also fire M80A1 Enhanced Performance Rounds or XM1158 Advanced Armor Piercing Rounds rather than sniper rounds. The marksman version is fitted with a simpler SIG TANGO6 1-6×24 telescopic sight to make quick adjustments between 0-600 m (0-656 yd) and features a red horseshoe dot for fast aiming and an illuminated Extended Range Bullet Drop Compensation (BDC) illuminated front focal plane reticle. It will also be fielded with a suppressor to lessen its sound signature. Roughly 6,000 are planned to be fielded with one per squad in infantry, engineer and scout formations. Early testing began with several U.S. Army combat units receiving the first M110A1 SDMRs in fall 2018. Fielding to all close combat squads is expected to be completed in late 2023.

Civilian

The MR308 is a civilian variant of the HK417, introduced in 2007 alongside the MR223, a civilian HK416. It is a semi-automatic rifle with several "sporterized" features. At the 2009 SHOT Show, the two rifles were introduced to the American civilian market as the MR762 and MR556, respectively. Since then, both were replaced by the improved MR762A1 and MR556A1.

2000s

• War in Afghanistan (2001-2021)
• Insurgency in the North Caucasus

2010s

• Armed conflict for control of the favelas in Greater Rio de Janeiro

2020s

• Russian Invasion of Ukraine