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.