XM8 Lightweight Assault Rifle (USA)

XM8 rifle in basic infantry configuration, as displayed in January, 2004, at the ShotShow-04 in USA

XM8 rifle in "automatic rifle" (light machine gun) configuration. Note longer barrel and folded bipods under the forearm

XM8 rifle in "sharpshooter" (parasniper) configuration. While sight looks similar to red-dot, mounted on other variants, it is of 3.5X magnification; spare magazine is clamped to the right side of the magazine inserted into the rifle.

XM8 rifle in Compact (SMG / PDW) configuration, with shortened barrel.

Author of this website is posing with XM8 at the ShotShow-2004, Las Vegas, USA.

Caliber: 5.56x45 mm NATO
Action: Gas operated, rotating bolt
Overall length: 838 mm in basic configuration, butt extended
Barrel length: 318 mm in basic configuration; also 229 mm in Compact and 508 mm in Sharpshooter and SAW versions
Weight: 2.659 kg empty in basic configuration
Rate of fire: ~ 750 rounds per minute
Magazine capacity: 30 rounds (STANAG) or 100-rounds double drum in Automatic Rifle/SAW role

The development of the XM8 Lightweight Assault Rifle was initiated by US Army in the 2002, when contract was issued to the Alliant Techsystems Co of USA to study possibilities of development of kinetic energy part of the XM29 OICW weapon into separate lightweight assault rifle, which could, in the case of success, replace the aging M16A2 rifles and M4A1 carbines in US military service. XM8 is being developed by the Heckler-Koch USA, a subsidiary of famous German Heckler-Koch company. According to the present plans, the XM8 should enter full production circa 2005, if not earlier, several years before the XM29 OICW. The XM8 (M8 after its official adoption) should become a standard next generation US forces assault rifle. It will fire all standard 5.56mm NATO ammunition, and, to further decrease the load on the future infantrymen, a new type of 5.56mm ammunition is now being developed. This new ammunition will have composite cases, with brass bases and polymer walls, which will reduce weight of the complete ammunition, while maintaining compatibility with all 5.56mm NATO weapons. Along with 20% weight reduction in the XM8 (compared to the current issue M4A1 carbine), this will be a welcome move for any infantryman, already overloaded by protective, communications and other battle equipment.

The XM8 will be almost similar to the "KE" (kinetic energy) part of the XM29 OICW system, being different mostly in having a telescoped plastic buttstock of adjustable length, and a detachable carrying handle with the sight rail.

As of mid-2004, XM8 now is undergoing wide-scale testing in several units of US Army, and is receiving a positive feedback.

XM8 status update (September 2005): Following several complains about non-competitive procurement of the XM8 system from Heckler-Koch USA, US Army first opened the bidding for contract to other companies, and then, in the July 2005, suddenly suspended the entire OICW Increment 1 program to re-think the entire set of requirements for the possible replacement of current M16 rifles and M4 carbines. These requirements will be re-viewed as Joint Services effort. At the present time, it seems that development of HK XM8 is suspended; it may be resumed if XM8 suit the new US Joint Service Requirements for a new assault rifle system; or, it may not. We will watch this process closely and update this article when new information will be available.

Technical description.
The XM8 is a derivative of the Heckler-Koch G36 assault rifle, and thus it is almost similar to that rifle in design and functioning. XM8 features a short piston stroke, gas operated action, with rotating bolt locking. Barrels are quick detachable, and planned to be available in several sizes, ranging from 229 mm (9.5 inch) for Compact/PDW version, 318mm (12.5 inch) in Basic version, and two 508mm (20in) barrels, one for Sharpshooter/Sniper version, and heavier one (along with bipod) for Squad Automatic Rifle role. The entire construction is modular and built around the polymer receiver with bolt group; Magazine housings could be easily swapped for compatibility with various types of magazines; various buttstocks could be installed in a second for various roles (standard buttstock is a telescoped 5 position adjustable one). Top of the receiver is fitted with proprietary sight rail, which can accept illuminated red-dot (collimator) sight, or any other type of sighting equipment. Detachable forend will be available in various sizes, and could be replaced with XM320 40mm grenade launcher (the improved HK AG36).

Ambidextrous fire controls are mounted on the trigger unit, integral with pistol grip and triggerguard, and in basic configuration are planned to deliver single shots and full auto fire. The G36-type ambidextrous charging handle is located at the top of the receiver, below the removable carrying handle.

SIG 716 tactical rifle (USA)

SIG 716 Patrol rifle with EOTech red-dot and back-up iron sights, as displayed at ShotShow 2010

	SIG 716 Patrol	Sig 716 Precision Sniper
Caliber:	7.62x51 NATO / .308 Winchester
Action	Gas operated, short stroke piston, rotary bolt locking
Overall length	? mm	? mm
Barrel length	406 mm / 16"	504 mm / 20"
Weight, less magazine	? kg	? kg
Rate of fire	n/a	n/a
Magazine capacity	10 or 20 rounds

The family of SIG 716 Tactical rifles is a most recent product of the US-based branch of the international arms maker SIG-Sauer. This family reflects current resurrection of the interest toward 7.62mm NATO / .308 Win weapons among US and other NATO troops, currently operating in Afghanistan and Iraq. It also targets to US domestic LE and civilian markets, as the SIG 716 family of rifles includes both Selective-fire (LE/Military only) and Semi-automatic (Civilian legal) guns. The SIG 716 Tactical rifles are closely patterned after the Ar-15 / M16 family of rifles, but are somehow bigger due to the bigger and more powerful caliber, and with certain improvements, such as piston-operated gas action with adjustable gas regulator. The SIG 716 Tactical rifles can be considered to be bigger brothers to the very similar family of SIG 516 tactical rifles, which are chambered for 5.56mm / .223 caliber ammunition. Obviously, it also will compete against such 7.62mm rifles as HK 417, FN SCAR/H Mk.17 and a variety of other 7.62mm Ar-15 / M16 knock-offs. The rifles shown here are prottypes, and it is believed that production rifles will begin to appear on US market not earlier than 2011.

The SIG 716 Tactical rifles are gas operated weapons that use Ar-15 / M16 configuration, with aluminum alloy upper and lower receivers assembled by two captive cross-pins. The basic Ar-15 / M16-style rotary bolt gas operated action is enlarged and strengthened to work with more powerful 7.62mm / .308 caliber ammo and improved with addition of the short-stroke gas piston that runs inside handguards, above the barrel. The gas block is equipped with manually adjustable gas regulator. The trigger unit, manual safety and feed system (magazines, bolt release etc) are also similar to the Ar-15 / M16. The SIG 716 Patrol rifles feature shorter 16 inch barrels and adjustable M4-type buttstocks. The SIG 516 Precision Sniper rifles have longer 20-inch heavy profile barrels and adjustable 'sniper' stock. In either version, barrels are chrome-lined. The sighting equipments is installed using integral Picatinny rail on the top of the receiver and on the additional 4 rails on the forend.
Military / LE only selective fire versions feature full-automatic and/or 3-round burst firing modes, civilian SIG 716 rifles will fire only in semi-automatic mode. SIG 716 rifles are compatible with current Armalite AR-10 Gen.2 magazines, which are available in 10- or 20-round capacities.

SIG 516 tactical rifle (USA)

SIG 516 Patrol rifle

SIG 516 Precision Marksman rifle

	SIG 516 Patrol	Sig 516 Precision Marksman
Caliber:	5.56x45 NATO / .223 Remington
Action	Gas operated, short stroke piston, rotary bolt locking
Overall length	920 ... 947 mm	914 ... 1003 mm
Barrel length	406 mm / 16"	457 mm / 18"
Weight, less magazine	3.3 kg	3.5 kg
Rate of fire (for MIL / LE versions only)	750 - 900 rounds per minute	n/a
Magazine capacity	30 rounds

The family of SIG 516 Tactical rifles is a most recent product of the US-based branch of the international arms maker SIG-Sauer . Intended primarily for the US markets, this family of weapons included two basic semi-automatic versions, intended for civilian and Law Enforcement markets. The same family also includes selective-fired "assault rifles", strictly intended for Government (LE and Military) use. The SIG 516 Tactical rifles are closely patterned after the Ar-15 / M16 family of rifles, but with certain improvements, such as piston-operated gas action with adjustable gas regulator. It is possible that select-fire version of the SIG 516 rifle will also compete for replacement of the current US Army's M4 carbine.

The SIG 516 Tactical rifles are gas operated weapons that use Ar-15 / M16 configuration, with aluminum alloy upper and lower receivers assembled by two captive cross-pins. The basic Ar-15 / M16-style rotary bolt gas operated action is improved with addition of the short-stroke gas piston that runs inside handguards, above the barrel. The gas block is equipped with manually adjustable gas regulator. The trigger unit, manual safety and feed system (magazines, bolt release etc) are also similar to the Ar-15 / M16. The SIG 516 Patrol rifles feature shorter 16 inch barrels and adjustable M4-type buttstocks. The SIG 516 Precision Marksman rifles have longer 18-inch barrels and adjustable 'sniper' stock. In either version, barrels are chrome-lined. The sighting equipments is installed using integral Picatinny rail on the top of the receiver and on the additional 4 rails on the forend.

Armalite AR-18 assault rifle (USA)

original AR-18 assault rifle, made by the Sterling Armaments of UK

the "reincarnated" AR-180B of recent manufacture. Semi-automatic only and with plastic lower receiver with integral pistol grip

Schematic view of the AR-18 (from the original Armalite patent, issued in 1968)

Caliber: 5.56x45 mm (.223 Remington M193)
Action: Gas operated, rotating bolt
Overall length: 940 mm (738 mm with folded stock)
Barrel length: 464 mm
Weight: 3.09 kg with empty 20 rounds magazine
Magazine capacity: 20, 30 or 40 rounds

The AR-18 rifle had been developed by the Armalite company (USA) by the George Sullivan, Arthur Miller and Charles Dorchester in the early 1960s. This rifle was designed for the international military market as a replacement for the AR-15 project, which had been sold to the Colt in 1959 by the Armalite's parent company, Fairchild Aircraft and Engine Corp. The AR-18 was designed as a competitor to the AR-15, which could be made at much less expenses and on simplified machinery, with the view to sell the manufacturing licenses for AR-18 to the third world countries. The AR-18 was a really successful design from a technical standpoint, but it come out too late to compete with both officially accepted and adopted AR-15/M16 rifle of American origin and already widespread AK-47 rifle of the Soviet origin. The Armalite company by itself made very few specimens of this rifle. The manufacturing license was consequently sold to the British company Sterling Armaments Co and to the Japanese company Howa Machinery co, but all three companies produced hardly over 20 000 rifles total, and the production of the AR-18 was ceased circa 1979 for some 20 years. It was originally available in the military AR-18 (selective fire) and AR-18S (selective fire, with short barrel) versions, and in AR-180 semi-automatic only version. But in the year 2001 the Armalite company resurrected the AR-180 design, in somewhat modified form. New rifle, intended mostly for the civilian and law enforcement markets, featured the same AR-18 layout and action, but discarded the stamped steel lower receiver and replaced it with the plastic lower, with AR-15-compatible magazine housing and AR-15-type trigger unit, which allowed for wider spare parts availability. The original folding buttstock and flash suppressor are replaced with the plastic fixed buttstock of the same shape and the muzzle recoil compensator, to comply with the current US firearms laws. The price of AR-180B is slightly lower than of the similar basic AR-15 type rifle, and the available user reports about AR-180B are generally quite positive.

The most interesting point about the AR-18 is that, while being a commercial failure, it served as a platform for some further development, which took place in various countries. First, the AR-18 design obviously served as a starting point for the ill-fated British SA80 / L85 bull-pup assault rifle, which can be loosely described as a bullpup-ed and weakened AR-18. Second, the AR-18 served as a starting point for the Singapore SAR-80 assault rifle, designed by the Chartered Industries of Singapore with the help of the George Sullivan (who designed the AR-18 itself). And third, the relatively new German Heckler - Koch G-36 assault rifle bears a lot of similarity internally to the AR-18.

Technical description.
The AR-18 is a gas operated, magazine fed, air cooling selective fire rifle. The gas action features a short piston stroke, rotating bolt locking mechanism. The gas chamber and piston are located above the barrel, and the piston has the cupped head and its own return spring. The square-shaped bolt carrier is mounted inside the receiver on two guide rods, with each rod carrying its own return spring. Both rods are linked by the special end plates so the whole bolt / bolt carrier / return springs / guide rods assembly can be removed from the rifle as a single unit, which greatly simplifies the field maintenance. The rotating bolt is somewhat similar in construction to the AR-15 bolt, and is rotated by the bolt pin, which is engaged in the curved cam track, cut in the bolt carrier. The charging handle is fixed to the right side of the bolt carrier and reciprocates when gun is fired.

The receiver is made from stamped sheet steel and consists of two parts - upper and lower. Both halves of the receiver are hinged one to another at the front of the receiver. The upper and lower parts are interlocked by the rear ends of the bolt carrier guide rods. AR-18 is field stripped by pressing the guide rods forward by the special lever at the rear of the receiver, then by the folding the lower receiver down and forward.

The controls consist of the trigger, safety - fire mode selector at the left side of the receiver (similar to one found on AR-15 / M16 type rifles), and the bolt stop. The available fire modes are single shots and full auto, or only single shots in AR-180 and AR-180B.

The forearm, the pistol grip and the buttstock are made from black plastic. The buttstock folds to the side to save the space, if required, and AR-15 can be fired with butt folded. The sling attachment points are located on the barrel, just ahead of the forearm, and at the butt of the pistol grip, so the sling position is not affected by the position of the foldable buttstock.

The sights consist of the hooded front post and the "L"-shaped flip-up diopter rear, also protected from sides by large "dog ears". Each AR-18 also was fitted with the scope mount at the top of the receiver by standard.

Ruger AC-556 assault rifle / Mini-14 GB rifle (USA)

Ruger AC556 assault rifle with 30-round magazine. Note the fire mod selector at the rear of receiver, above the trigger

Ruger AC556F assault rifle, with short barrel, 20-round magazine and stock opened

Ruger AC556F assault rifle, with stock folded

Ruger Mini-14/GB "paramilitary" rifle, less magazine

Ruger Mini-14/GB-F "paramilitary" rifle with folding stock, full-length barrel and 30-round magazine. Note lack of fire selector on receiver

Ruger Mini-14 rifle, original version (1980's production) with aftermarket magazine

Ruger Mini-14 "Ranch" rifle of pre-2005 production. Note receiver with integral scope mounts and folding rear sight

Ruger Mini-14 rifle, current version (as made since 2005). Note different front and rear sights and polymer handguard which covers most of the operating rod;

Ruger Mini-30 "Ranch" rifle of current manufacture, with polymer stock

Caliber: 5.56x45mm NATO (.223 Remington); also 7,62x39 M43 in Mini-30
Action: Gas operated, rotating bolt
Overall length: 943 mm (851 / 603 mm for AC-556F)
Barrel length: 470 mm (330mm for AC-556F)
Weight: 2,9 kg empty
Magazine capacity: 5, 10, 20 or 30 rounds detachable box magazines
Rate of fire: 750 rounds per minute (for AC-556 only)

Bill Ruger, one of leading US arms designers of post-WW2 period, began development of a new semi-automatic rifle circa 1970. The rifle was intended for either civilian and para-military use; it was patterned after current US issue military rifle, the M14, and was chambered for relatively new 5,56x45mm (.223 Remington) ammunition. Since its commercial introduction in 1973 the Ruger Mini-14 rifle found wide acceptance among both civilian shooters and a variety of police and security forces around the world. For government users, Ruger produced two specialized versions of the basic rifle - the Mini-14GB and AC-556. The former is still a semi-automatic only weapon, but is fitted with protected front sight, flash-hider and a bayonet lug. The latter is a selective-fired weapon, and thus can be classified as a true assault rifle. All weapons in the Mini-14 family share same basic design, although there are differences in certain parts; for example, AC-556 rifles had slightly longer receiver, which hosts the fire mode switch at its rear part.
The first major modification to the Mini-14 family appeared in 1978, when Ruger introduced an all-stainless version of the basic rifle. Until now, all Ruger Mini-14 rifles are available either in carbon or stainless steel versions. In around 1982 Ruger introduced its next civilian modification of the Mini-14, known as the "Ranch" rifle. This version was optimized for use with telescope sight, and thus was produced with integral scope bases on receiver. Ejection mechanism was changed to eject spent cases to the right side, clear of the scope, and rear sight was fitted on the folding base. In 1986, Ruger introduced a Mini-30 rifle, which was same basic weapon but adapted to 7,62x39 M43 ammunition of Russian origin. The last change in the Mini-14 line-up appeared as late as in 2005, when Ruger company introduced a new version of the Mini-14, which incorporated integral scope bases of the earlier "Ranch" rifles with protected front sight and non-folding diopter rear sight, which has smaller mount that of previous rifles.
In general, Mini-14 rifles are known for their good reliability and durability. Accuracy is usually quoted as somewhat inferior to AR-15 (M16)-type weapons, which are very popular in USA; however, Mini-14 rifles are accurate enough for most purposes, and are excellent weapons for hunting, home defense, and general plinking.

Ruger Mini-14 is gas operated, semi-automatic only weapon which uses Garand-type rotary bolt with two lugs. Action is operated by the long-stroke gas piston, which is located below the barrel and is concealed within forend of the stock. The gas piston has cup-shaped head, and is linked to the bolt via Garand-type operating rod which runs at the right side of the weapon. Manual safety also patterned after M1 Garand or M14 rifle, and is located at the front of the triggerguard. The selective-fire AC-556 hosts fire mode selection mechanism at the rear of the somewhat lengthened receiver. Fire mode selector is a separate switch on the right side of receiver, behind the ejection port. It has three positions - for single shots, 3-round bursts and full automatic fire.
Standard stock of the Mini-14 is of single-piece type, with semi-pistol grip and separate heatshiled above the barrel. Early Mini-14 rifles had wooden heatshiled which exposed operating rod; military-type Mini-14GB and AC-556 rifles, as well as current production civilian guns, feature polymer heatshields which over most of the operating rod. Over the time, Ruger also produced a folding-stock versions with wooden stock, plastic pistol grip and side-folding metallic shoulder stock. Ruger also makes "all-weather" polymer stocks for Mini-14 and Mini-30 rifles. It also must be noted that there are many aftermarket stocks for Mini-14 rifles.
Standard sights consist of a blade-type front and adjustable diopter-type rear sight; "Ranch" type rifles also had integral scope mounts on the receiver, which will accept proprietary Ruger scope rings.
Original magazine capacities for Mini-14 rifles were 10 or 20 rounds, but since infamous American "Assault weapons ban" of 1994 Ruger offered civilian Mini-14 rifles with magazines containing only 5 rounds; however, some magazine makers produced aftermarket magazines for Mini-14 and Mini-30 in capacities of up to 40 (box) and 90 (snail-drum) rounds.