Zastava M76

The Zastava M76 is a military semi-automatic designated marksman rifle developed and manufactured by Zastava Arms.
History.
The Zastava Arms Company released the M76 in the mid-1970s. Since then it became the standard issue designated marksman rifle in the Serbian army and its predecessor the Yugoslav National Army (JNA). It was designed to fulfill the same role as the Soviet Dragunov SVD, which was to provide a designated marksman capability to the infantry platoon. During the Yugoslav Wars of the 1990s, it was used by several sides; it saw action in Croatia, Bosnia, Macedonia and Kosovo.
In Serbian service The M76 is reportedly being replaced by the Zastava M91. The Zastava M91 uses the 7.62×54mmR cartridge which is replacing the 7.92×57mm Mauser (M49/M75) cartridge in Serbian service.
Design details.
The M76 is similar in concept to the Russian Dragunov SVD sniper/designated marksman rifle; a semi-automatic rifle using a full-power cartridge from a 10-round magazine. However, the M76 is closer to the AK-47/RPK design than the Dragunov, similar to the Romanian PSL. Being derived from the AK design it is simple and reliable, and like other Zastava AK-derivatives it is of high-quality manufacture. Accuracy is typically around 1.5 MOA, which is good for a Kalashnikov design and entirely acceptable for the designated marksman role.
Rather than being a Dragunov clone, it looks more like a lengthened AK-47 with a heavier barrel, an impression strengthened by the separate stock and pistol grip rather than the Dragunov's thumbhole combination stock. Instead of the Dragunov's 7,62×54mmR chambering it uses the 7.92×57mm Mauser a.k.a. the 7.9mm or 8×57mm IS round. The Yugoslav National Army (JNA) adopted a 7.9mm Cartridge, Ball M49 variant, designated as M49, as infantry ammunition at the end of the 1940s and later a 7.9mm Cartridge, Sniper, with Universal ball M75, as sniper ammunition, designated as M75.
Instead of the Dragunov's separate gas piston, the M76 has an AK-type piston attached to the bolt carrier. The receiver is a milled forging like that of the original AK-47 to give greater rigidity when firing a full-power round and it is longer than the normal AK receiver to suit the 7.92×57mm Mauser chambering. The AK-type rotating bolt, bolt carrier, barrel and other parts are also enlarged and stronger for handling the bolt thrust full-power rounds produce. Feeding is via a 10-round steel box magazine, which has a follower that holds the bolt open after the last shot. Since there is no device in the weapon to hold the bolt to the rear, the bolt will move forward when the magazine is removed, which increases the difficulty of removing the magazine. Fire is semi-automatic only, so the AK-47-type safety on the right side of the receiver has only 2 settings - 'safe' and 'fire'. The barrel has a tapered profile with a Dragunov-type combination slotted flash suppressor and foresight housing. A standard AKM bayonet can be fitted to the bayonet lug below the foresight. Like the Dragunov, but unlike the AK-47, the M76 features a 4-position (0, 1, 2, 3) operator-adjustable gas regulator enabling more propellant gas to be vented to the piston in marginal operating conditions or less propellant gas when using a suppressor. The "0" setting entirely blocks the gas impulse to the piston, enabling use of the rifle as a manual repeater.
The furniture features a straight comb butt, which has a rubber pad similar to that found on the Zastava M70 series of weapons, and a well-shaped contoured pistol grip. The fore-end is also reminiscent of that found on the M70 series. There is no butt trap for cleaning kit storage in the wooden butt. In newer production models the wooden furniture is replaced with synthetic polymer material which offers some storage space for accessories like a cleaning kit and reduces the M76 overall weight by approximately 0.5 kg.
With the minor exception of the gas regulator, disassembly and operation are similar to that of the AK-47/AKM family of weapons.
Though the M76 fires its bullets at a relatively modest muzzle velocity, the 8×57mm IS cartridge loaded with aerodynamically efficient military sS ball bullets still offers a supersonic reach of ≈ under ICAO Standard Atmosphere conditions at sea level (air density ρ = 1.225 kg/m3). By way of comparison the standard ball round for the 7.62×51mm NATO round is 147gr, and sniper rounds are around 168gr - 173gr, so the M76 round has greater mass.
To mount the optics, a side-rail is permanently attached to the left wall of the receiver which accepts an alloy sliding dovetail rail mount with a clamping lever to which can be attached various telescopic sights and night optics. The mount is detachable from the receiver rail in seconds by swinging the locking lever open and sliding the scope and mount off the rail to the rear. It can be removed and reattached without loss of zero. The optic sight is normally removed during field stripping to give easy access to the receiver cover and bolt carrier. The rifle features mechanically adjustable backup AKM-type iron sights with a sliding tangent rear sight which can be adjusted from 100 m to 1,000 m. These sights can be used with or without the optic sight in place.
The typical scope used is a ZRAK ON-M76 4× 5°10′ scope originally produced in the ZRAK factory in Sarajevo, Bosnia and Herzegovina. This optical sight is similar to the PSO-1 4×24 sight used on the Russian SVD rifle and the Romanian I.O.R. LPS 4×6° TIP2 4×24 sight used on the PSL rifle.
The ON-M76 elevation turret features bullet drop compensation (BDC) in 50 m increments for engaging point and area targets at ranges from 100 m up to 1,000 m. The BDC feature must be tuned at the factory for the particular ballistic trajectory of a particular combination of rifle and cartridge (the 7,9 M75 sniper ammunition) at a predefined air density. Inevitable BDC induced errors will occur if the environmental and meteorological circumstances deviate from the circumstances the BDC was calibrated for. Marksmen can be trained to compensate for these errors. Besides the BDC elevation or vertical adjustment control of the reticle, the windage or horizontal adjustment control of the reticle can also be easily dialed in by the user without having to remove turret caps etc.
The reticle illumination of the ZRAK M76 4× 5°10′ is provided by (radioactive) tritium. The tritium light source has to be replaced every 8–12 years, since it gradually loses its brightness due to radioactive decay. The reticle features a PSO-1 type range-finding reticle.
Performance.
The M76 is relatively accurate for a semi-automatic rifle. It can achieve 1.5 to 2 Minute of angle using standard surplus ammunition or MOA consistent accuracy with higher quality ammunition. Under normal conditions a maximum effective range of against man sized targets for an average sniper is achievable. The dispersion at is described as 50 × 50 cm (19.7 × 19.7 in), which is ≈ 1.9 MOA. Under optimal atmospheric and environmental conditions excellent marksmen might use the M76 up to . Recoil is described as being modest.
It has the reputation of a reliable and capable weapon and has seen extensive combat service. 
There is a known issue, however, with the magazines of the M76 being unreliable. Due to the bolt hold open property of the magazines, the bolt will slam forward when the magazine is removed, putting considerable pressure on the follower. This can result in the follower being jammed in the forward position, rendering the magazine temporarily inoperable.
Variants.
Zastava Arms currently offers a civilian variant in .308 Winchester called the LKP M76, which they designate as a semi-automatic sporting rifle. The only other variant is the Iraqi Tabuk sniper rifle, made under Zastava license, chambered for 7.62×39mm cartridges. Assault Weapons of Ohio builds M76 variants in .30'06 and 8mm calibers.