The SVD bears a number of cosmetic similarities to the
AK family of rifles but these similarities are for the purpose of standardizing manual of arms. This has occasionally led to misidentification of the SVD as an AK variant, and vice versa.
Operating mechanism The barrel breech is locked through a
rotating bolt (left rotation) and uses three locking lugs to engage corresponding locking recesses in the barrel extension. The rifle has a hammer-type striking mechanism and a manual lever safety selector. In addition to the trigger disconnect, the fire control mechanism has a second disconnector which does not allow the hammer to fall until the bolt has been closed, similar to a
sear in a select-fire weapon. However, the SVD was only designed for semi-automatic fire. The firing pin in the SVD is not retained, i.e. "free-floating", and it is therefore possible for accidental discharge to occur as the bolt pushes an unfired cartridge into the chamber, should there be an obstruction in the firing pin channel resulting from poor maintenance or extreme cold. The firearm is operated by a
short-stroke gas piston system with a two-position gas regulator. The gas regulator can be set with the help of the rim of a cartridge. Position #1 leaves a gas escape port opened, whereas position #2 closes the gas escape port and directs extra gas to the piston, increasing the recoil velocity of the gas-piston system and is used for resolving reliability issues, which arise from fouling in the gas port/action, extreme cold, high altitude, or using under-powered ammunition. The rifle is fed from a detachable curved
box magazine with a 10-round capacity and the cartridges are double-stacked in a staggered zigzag pattern. After discharging the last cartridge from the magazine, the bolt carrier and bolt are held back on a bolt catch that is released by pulling the cocking handle to the rear. The rifle's
receiver is
machined to improve precision by adding
torsional strength.
Barrel The
barrel profile is relatively thin to save weight. Its bore is
chrome-lined for increased corrosion resistance and features four right-hand grooves. Originally, the
twist rate was 320 mm (1:12.6 in), as it had been designed for use with heavier civilian ammunition. In 1975 the twist rate was increased to the standard 240 mm (1:9.4 in), which reduced the precision with the 7N1 sniper cartridge by 19% but allowed for the use of standard "light" ball steel core LPS Gzh (57-N-323S), as well as its variations (incendiary, tracer, armour-piercing) with acceptable precision. The front part of the barrel features the front
sight assembly and a
bayonet lug. The muzzle is equipped with a permanently affixed long-slotted
flash hider. In order to pass inspections at the factory, these rifles must not produce more than a 0.7 MOA median deviation from the expected point of impact in three 10-shot groups using 7N1 (approximately 3 MOA).
Ammunition To enable the SVD's desired precision, new 7.62×54mmR "sniper" ammunition, designated 7N1, was designed by V. M. Sabelnikov, P. P. Sazonov and V. M. Dvorianinov in 1966 to meet the new standards. 7N1 sniper cartridges should not produce more than 1.24
MOA extreme vertical spread with 240 mm twist rate barrels and no more than 1.04 MOA extreme vertical spread with 320 mm twist rate barrels in a 5-shot group. The precision requirements demanded of the SVD with 7N1 is similar to the American
M24 Sniper Weapon System with M118SB cartridges (1.18 MOA extreme vertical spread) and the
M110 Semi-Automatic Sniper System with M118LR ammunition (1.27 MOA extreme vertical spread). 7N1 differed from the standard LPS Gzh (57-N-323S) cartridge in its use of finely extruded propellant and a modified projectile containing a void inside of the jacket at the tip which improved terminal ballistics and a bimetal lead and mild steel core. With standard 57-N-323S cartridges, the precision of the SVD is reduced to 2.21 MOA extreme vertical spread. This ammunition was later replaced by 7N14 in 1999, which replaced the mild steel penetrator with a hardened steel penetrator in response to the development of infantry body armour.
Sights 's unique reticle. The rangefinder is in the lower left, chevrons for distances beyond are found in the middle, and stadia marks for windage are to the left and right of the center reticule. The reticle is illuminated by a small battery-powered lamp. The rifle features adjustable
iron sights with a sliding tangent rear sight, graduated from in increments. The iron sights can be used with or without the standard-issue optical sight in place. This is possible because the
scope mount does not block the area between the front and rear sights. The SVD was originally issued with a detachable
PSO-1 optical sight (later upgraded and semi-issued as the PSO-1M2), which mounts to a
Warsaw Pact rail on the left side of the receiver. The PSO-1 elevation turret features
bullet drop compensation (BDC) in or increments for engaging point and area targets at ranges from up to . At longer distances, the shooter must use the chevrons that would shift the trajectory by per each chevron. The BDC feature must be tuned at the factory for the particular ballistic trajectory of a particular combination of rifle and
cartridge at a predefined
air density. With increasing range, inevitable BDC-induced errors will occur when the environmental and meteorological circumstances deviate from the predefined circumstances for which the BDC was calibrated. Marksmen can be trained to understand the
main forces acting on the projectile and their effect on their particular gun and ammunition, and the effects of
external factors at longer ranges to counter these errors. The PSO-1 sight enables area targets to be engaged at ranges upwards of ; effective ranges in combat situations have been stated at between , depending on the nature of the target (point or area target) quality of ammunition and skill of the shooter. Several military issue alternative telescopic sights with varying levels of magnification and reticles are available for the SVD. Rifles designated
SVDN come equipped with a night sight, such as the NSP-3, NSPU, PGN-1, NSPUM or the Polish passive PCS-5. Rifles designated
SVDN-1 can use the passive night sight NSPU-3 (
1PN51) and rifles designated
SVDN2 can use the passive night sight NSPUM (
1PN58). Commercial non military issue mounts that attach to the Warsaw Pact rail mount can allow use of
Picatinny rail-mounted optics.
Stock The original SVD had a
birch plywood laminate two-piece handguard/gas tube cover and a skeletonized thumbhole stock equipped with a detachable cheek rest; the latter is removed when using iron sights. Beginning in the 80's, wooden parts were replaced with synthetic parts made of a black
polymer – the handguard and gas tube cover are more or less identical in appearance, while the thumbhole stock is of a different shape.
Accessories mounting system.A number of accessories are issued with the rifle, including a blade-type
bayonet (
AKM clipped point or the
AK-74 spear point bayonet), four spare magazines, a leather or nylon sling, magazine pouch, cleaning kit and an accessory/maintenance kit for the telescopic sight. Also included is a cold weather battery case with a "shirt clip", with a permanently attached cord [approximately 24" long] ending with another battery case cap that has an extension to press against the internal contact in lieu of the battery to complete the circuit. Placing the external battery case into the shooters' clothing close to the body keeps it from freezing; using the clip ensures it remains in place. The clamp-style bipod attaches to machined-out reliefs near the front of the receiver, it literally grabs the two cut out areas and securely mounts with a large round sized head on the clamp bolt able to tightly attach the bipod. The legs are individually adjustable [as opposed to fixed length found on many rifles and LMGs] and can be folded and stowed in a forward position negating the need to remove the bipod before placing the rifle into the canvas carrying case. The two legs are held close together with a J-shaped clamp attached to one leg and swung over the other leg. Original Soviet/Russian SVD bipods fetch a very high price when they rarely appear on the market. ==Variants==