Playerunknown's Battlegrounds is a survival shooter designed by Brendan "Playerunknown" Greene, the same person who created the Battle Royale mod for Arma 3 and was consulted in the creation of H1Z1: King of the Kill. In Battlegrounds, up to 100 players are airdropped onto a fictional locale, and fight until only one remains, with a blue wall of electricity chasing players into one final confrontation. Weapons are customizable with various parts that can be found in the field. Some attachments have a weapon specific variant of them. For example, the flash hider has a version for SMGs and assault rifles. These attachments include:
Various foregrips
Laser Sights
Flash hider (SMG/Sniper rifle/DMR/AR, S12K): reduces the weapon's muzzle flash
Suppressor (Pistol/SMG/Sniper rifle/DMR/AR, S12K): Suppresses the weapon's muzzle report, but does not completely silence it, being somewhat realistic in its function.
Compensator (SMG/Sniper rifle/DMR/AR, S12K): Reduces muzzle climb during automatic fire.
Choke: tightens the pellet spread of the shotguns.
Duckbill: horizontally flattens the pellet spread of the shotguns.
Bullet loops: enhances reload speed by adding a shell/cartridge holder on the buttstock of the weapon.
Ext. Quickdraw magazine (Pistol/SMG/Sniper rifle/DMR/AR, S12K): combination of the two above
Cheek pad: reduces scope sway while aiming
Tactical stocks: improves weapon handling and recoil control
Folding Stock for the Uzi and Skorpion: ditto.
Sights featured are the:
Red dot sight
Holographic sight
2x Aimpoint scope
3x Backlit scope
4x ACOG scope
6x scope
8x CQBSS scope
15x PM II scope
As similarly seen in the game State of Decay, ammunition calibers in PUBG are simplified for the sake of gameplay. For instance, the SKS, AKM, M24, Kar98k, DP-28 and the Nagant revolver all fire the same "7.62MM" ammunition, and the 9x39mm VSS Vintorez uses the same "9MM" ammo as the 9x19mm handguns and submachine guns.
Handguns
Beretta 92F
The Beretta 92F appears in the game as the "P92", and can be found in random buildings. It can be fitted with a suppressor, a laser sight, a red dot sight and all three magazine variations. It uses general "9MM" ammunition. Extended magazines raise the magazine size to 20 cartridges from its original 15.
Chiappa Rhino 60DS
The Chiappa Rhino 60DS appears in the release version of the game as the "R45", and will be found in random locations exclusive to the maps; Miramar and Sahnok. It can be fitted with a red dot sight, a laser sight, and is apparently chambered in ".45ACP" ammo with speedloaders.
Colt M1911A1
The Colt M1911A1 appears in the game as the "P1911", and can be found in random buildings. It can be fitted with a suppressor, a laser sight, a red dot sight and all three magazine variations. It uses general ".45ACP" ammunition. Extended magazines raise the magazine size to 12 cartridges from its original 7.
Desert Eagle Mark XIX
The Desert Eagle was added in the June 2019 update and goes by its common moniker, "Deagle" but somehow fires ".45ACP" ammunition. It is a rare spawn in all maps and can also be equipped with all magazine variants, laser sights and red dot or holographic optics. Extended magazines raises the magazine size to 10 cartridges from its original 7 which is consistent with the .50 AE variant, although the cartridges that eject from it appear to be thinner .357 Magnum rounds.
Glock 18C
The Glock 18C was added in the June 2017 monthly update, as the "P18C". It can be fitted with suppressor, a laser sight, a red dot sight and all three magazine variations, as well as being able to switch between semi and full-auto fire modes. It uses general "9MM" ammunition. Extended magazines raise the magazine size to 25 cartridges from its original 17. Like most of the guns in the game, the fire selector is animated.
Nagant M1895
The Nagant M1895 appears as the "R1895", and can be found in random areas exclusive to the maps; Erangel and Sahnok. It can be fitted with a suppressor, which is possible and viable with the real gun as well due to its ammunition and firing mechanism. It uses general "7.62MM" ammunition, which curiously can be used in rifles as well.
Orion Flare Gun
The Orion Flare Gun was initially added to the game in March 2018 during an Event Mode, but as of 2019, it was integrated into the main game as a rare spawn pickup. It occupies the sidearm slot and uses propriety "Flare" ammunition but does no damage to players or vehicles. It can only be used by firing straight up into the air which then calls in an airdrop containing several crate weapons and equipment, or an armored UAZ-469 if the user is within or outside the Blue Zone.
Submachine Guns
Heckler & Koch MP5KA4
The Heckler & Koch MP5KA4 was added in the March 2019 Update #27, appearing exclusive to the Vikendi map, replacing all TDI Vector spawns there. It is chambered in "9mm" and can be fitted with foregrips or a laser sight, all muzzle devices and magazine variants, the tactical stock, as well as all sights up to the 4x scope. Extended magazines raise the magazine size to 40 cartridges from its original 30.
Heckler & Koch UMP45
The Heckler & Koch UMP45 replaces the original "UMP-9" brother since the March 2019 Update #27, and is chambered for ".45ACP" ammunition. It can be fitted with foregrips or a laser sight, all muzzle devices and magazine variants, as well as all sights up to the 4x scope. Extended magazines raise the magazine size to 35 cartridges from its original 25.
IWI Uzi Pro
The IWI Uzi Pro has replaced the Micro Uzi since Update 4.1 in June 2019. It fires "9mm" ammunition as before and can be found in all maps simply as the "Uzi". It can also be equipped with all magazine variants, muzzle devices, a Micro Uzi's stock, and (thanks to the presence of a top rail) a red dot or holographic sight. Despite being modeled with a 20-round magazine, the weapon holds 25 rounds by default; extended magazines raise this to 35 rounds in what seems to be a 32-round magazine.
M1928/A1 Thompson
The M1928A1 Thompson appears in the game as the Tommy Gun, and is chambered for ".45ACP" ammunition. After the September 2017 update, the Tommy Gun was moved from a supply drop-exclusive weapon to an uncommon spawn all over the map. It can be fitted with a suppressor, a vertical foregrip and all magazine attachments. The vertical foregrip will essentially convert the appearance of the Tommy Gun to that of the earlier M1928 version, while the extended magazine attachments will increase its initial capacity of 30 rounds (in box magazines) to 50 rounds (in drum magazines).
Crossbow
The Thompson's model is, curiously enough, also used as the basis for the game's fictional crossbow. The crossbow, which is only ever referred to as such, is fitted with a green-dot sight with drop compensation markings by default, though it can be customized with normal red-dot or holographic sights, as well as a container of arrows underneath the arms, which somehow speeds up reloading despite never being used for anything.
PP-19 Bizon-2
The PP-19 Bizon-2 was added in the Feb 2019 patch and is only featured in the maps, Erangel and Vikendi. It is chambered for "9mm" ammunition in a 53-round helical magazine which confirms this as the 9x19mm variant. It can only be fitted with all muzzle devices and sights up to the 4x scope.
Sa. Vz.61 E Skorpion
The Sa. Vz.61 Skorpion is a machine pistol that appears in the game simply as the "Skorpion" and apparently chambered in "9mm" ammunition with select-fire capability, even though the firearm and its curved magazines appear to be modeled after the .32 ACP variants. It is the first full-sized machine pistol in PUBG to occupy the sidearm slot and can be found in random spawn locations. It can be equipped with the half/lightweight/vertical foregrips or a laser sight, suppressor, red dot sight, extended stock and only the extended magazine variant for pistols. Extended magazines raise the magazine size from 20-round stick magazines that can be upgraded to 40-round drum magazines.
TDI Vector
The TDI Vector appears in the game simply as the "Vector", and is now chambered for "9mm" ammunition, previously having used .45 ACP ammo before the March 2019 Update #27 . It can be fitted with half/lightweight/vertical foregrips or a laser sight, all muzzle devices, magazine variants, optics up to the 4x scope and a tactical stock. Extended magazines raise the magazine size to 33 cartridges from its original 19.
Shotguns
Beretta 686
The Beretta 686 appears in the game as the "S686", and can be found in random buildings. Note that unlike the picture below, it's completely blued and has golden bird engravings on the side of the receiver ingame. It can be fitted with a choke for a tighter pellet spread, as well as "bullet loops" for the stock for faster reloading. It has the longest effective range of all shotguns, especially with the choke. The reload animation shows that the gun has ejectors, and ejects two spent cases even if it's fired only once.
Winchester M1897
The Winchester Model 1897 appears in the game as the "S1897", and can be found in random buildings. It can be fitted with a choke or duckbill for a tighter pellet spread, as well as "bullet loops" for the stock for faster reloading.
Saiga 12K
The Saiga 12K appears in the game as the "S12K", and can be found in random buildings. It can use a duckbill choke, or otherwise is able to be fitted with all other assault rifle muzzle devices, scopes, a suppressor, as well as all magazine variants. The standard magazines holds 5 shells, while the extended magazines hold 8.
Sawed-off Shotgun
A 12 Gauge Double Barreled Shotgun in a sawed-off configuration appears in the release version of the game as the "Sawed-off" and can be found randomly in the map, Miramar. It is classified as a sidearm, and is chambered in "12 Gauge" and only able to use a shotgun choke as of the May 2018 update.
Rifles
Note: As of the May 2018 update, the now officially classed Designated Marksman Rifles (i.e. Mini-14, Mk 14, QBU-88, SKS, SLR and VSS) can now utilize both Assault Rifle and/or Sniper Rifle attachments interchangably. Assault rifles no longer have the capability of using the 8X and 15X scopes for balance reasons.
AKM
The AKM appears in the game under its actual name, and fires the game's mysterious "7.62mm" ammunition. It can be found in random buildings, and can be equipped with all magazine variants, sights sights up to 6x scope (as it has a picatinny rail on the receiver cover plate), and all muzzle devices.
Beryl M762
The M762 version of the Polish Kbs wz.96 Beryl is an assault rifle that appears in the game correctly as the "Beryl M762" and fires "7.62mm" ammunition. It can be found in random spawns locations and can also be equipped with all magazine variants, foregrips, muzzle devices a laser sight, and optics up to 6X. It features semi-auto, 3-round burst and full-auto firing modes.
CMMG Mk47 Mutant
The CMMG Mk47 Mutant is an assault rifle that appears in the game as the "Mk47 Mutant" and fires "7.62" ammunition. It can be found in all maps, at random spawn locations and can also be equipped with all magazine variants, foregrips or a laser sight, muzzle devices, a tactical stock and optics up to 6X. It only has semi-auto and 2-round burst firing modes (the latter being fictional, since the real weapon is either semi-auto only or semi-auto/full-auto) from a 20-round magazine that can be upgraded to 30 rounds with extended magazine attachments.
FN SCAR-L
The FN SCAR-L appears as the "SCAR-L" ingame, and fires the "5.56mm" ammunition. It can be found in random buildings, and can be equipped with all magazine variants, foregrips or a laser sight, muzzle devices, and optics up to 6X.
Heckler & Koch G36C
The Heckler & Koch G36C was added in the Dec 2018 update simply as the "G36C", exclusive to the map Vikendi (replacing the SCAR-L spawns) and fires the "5.56mm" ammunition. It can be equipped with all magazine variants, foregrips or a laser sight, muzzle devices and optics up to 6X.
Heckler & Koch HK416
The Heckler & Koch HK416 appears as the "M416" ingame, and fires the "5.56mm" ammunition. It can be equipped with all magazine variants, foregrips or a laser sight, muzzle devices, optics up to 6X, and the tactical stock.
L1A1 SLR
The L1A1 with picatinny rail on the upper receiver was added in the May 2018 update and appears in the game under the British Army designation of "SLR" and fires "7.62mm" ammunition. It can be found randomly in buildings and can be equipped with all the muzzle devices, sights, and scopes, a cheek pad, as well as an extended magazine increasing its capacity from 10 rounds to 20 rounds.
M16A4
The M16A4 appears under its actual name in-game and fires the "5.56mm" ammunition. It is fitted with a standard, non-railed handguard (as seen in the image below), and therefore cannot accept any foregrips. It can be found in random buildings, and can be equipped with all magazine variants, muzzle devices, a tactical stock and sights up to the 6X.
Mk 14 Mod 0
The Mk 14 Mod 0 Enhanced Battle Rifle was added in the August 2017 update as the "Mk14" and is only found in crates that are parachuted in, known as "Care Packages". It can be equipped with all the muzzle devices, sights, a cheek pad and scopes, as well as an extended magazine increasing its capacity from 10 rounds to 20 rounds. It is chambered in "7.62mm" ammunition and has fire-select capability between semi-auto and full-auto.
Norinco QBZ-95-1
The Norinco QBZ-95-1 was added in the Jun 2018 update as the "QBZ95" and is chambered in "5.56mm" ammunition, probably standing-in for its native 5.8x42mm ammunition (although its exported cousin, the QBZ-97 is chambered in NATO 5.56x45mm). It is an exclusive world spawn to the Sanhok map (replacing the FN SCAR-L there), and can be equipped with all magazine variants, foregrips or a laser sight, muzzle devices, and optics up to 6X.
OTs-14-1A Groza
The OTs-14 Groza was added in the June 2017 monthly update, as the "Groza" and is only found in crates that are parachuted in, known as "Care Packages". It is chambered in "7.62mm" ammunition (confirming it as a OTs-14-1A variant of the rifle), and can be equipped with all magazine variants, sights up to the 6X and a suppressor.
Ruger AC556
The folding stock variant of the Ruger AC556 appears in the September 2017 update as the "Mini 14". It indeed functions like a Ruger Mini-14 as it can only be fired in semi-automatic mode, but is modeled with (an unused) selector switch at the back of the receiver, which identifies it as an AC556. It fires "5.56mm" ammunition and accepts muzzle and magazines attachments, as well as all sights and scopes. Extended magazines increases its capacity from 20 rounds to 30 rounds.
SKS
The SKS rifle can be found in random buildings. Ingame, it is fitted with a Tapco Intrafuse stock and an aftermarket detachable magazine conversion. It can be equipped with all the muzzle devices, foregrips or a laser sight, scopes, a cheek pad and magazines. Extended magazines increases its capacity from 10 rounds to 20 rounds. It fires the "7.62mm" ammunition.
Steyr AUG A3
The Steyr AUG A3 with a custom lower rail appears simply as the "AUG" in the 1.0 release version of the game and can only be found in crates that are parachuted in, known as "Care Packages". It fires "5.56mm" ammunition, and can be equipped with all magazine variants, foregrips or a laser sight, optics up to the 6X and muzzle devices.
Winchester 1894
The Winchester 1894 appears in the release version of the game as the "Win94" exclusive to the map, Miramar. It is apparently chambered in ".45ACP" (presumably standing-in for .45 Long Colt) and can only equip a rifle bullet loop for quicker reloads. It has a capacity of 8 rounds.
Sniper Rifles
Accuracy International AWM
The Accuracy International AWM appears in the game as the "AWM", and is only found in crates that are parachuted in, known as "Care Packages." It can be equipped with a sniper rifle suppressor or a flash hider and all the sights and scopes, as well as an extended magazine and a cheek pad. Extended magazines increases its capacity of 5 rounds to 7 rounds. It fires the ".300" ammunition (presumably .300 Winchester Magnum, one of the cartridges that the AWM supports).
Karabiner 98k
The Karabiner 98k appears in the game as the "Kar98k", and can be found as a random world spawn. It can mount all of the sights, as it has a picatinny rail in place of its original rear sight. It also accepts all muzzle devices, and can be fitted with a cheek pad for reduced scope sway or rifle bullet loops for quicker reloads. It fires the "7.62mm" ammunition; while Wehrmacht-manufactured rifles were historically chambered in 7.92x57mm Mauser, many post-war Karabiner 98ks were indeed rechambered in 7.62x51mm NATO by the militaries of countries such as Israel and Norway. The player will reload the rifle with individual cartridges when there are rounds left in the magazine, but use stripper clips if all rounds are expended from the weapon.
M24A2 SWS
The M24A2 appears in the game as the "M24", and as of the May 2018 update, can now be found as a rare world loot spawn instead of "Care Packages". It can be equipped with a muzzle attachments, all the sights and scopes, as well as magazines and a cheek pad. Extended magazines increases its capacity of 5 rounds to 7 rounds. It fires the "7.62mm" ammunition.
Norinco QBU-88/KBU-97A
The Norinco QBU-88 is a designated marksman rifle added in the July 2018 update and appears in the game simply as the "QBU" and fires "5.56mm" ammunition, probably standing-in for its native 5.8x42mm ammunition (although its exported cousin, the KBU-97A is chambered in NATO 5.56x45mm). It is an exclusive world spawn to the Sanhok map (replacing the Ruger Mini-14 there) and comes with an attached bipod by default which promotes higher stability when prone. It can also be equipped with all the muzzle devices, sights as well as an extended magazine increasing its capacity from 10 rounds to 20 rounds.
VSS Vintorez
The VSS Vintorez appears in the game simply as "VSS" and as of the July 2017 update, can only be found as a rare loot spawn instead of "Care Packages". It is classified as a designated marskman rifle, therefore it can only be equipped with a cheek pad and AR/DMR or SR magazine attachments, as it comes with its integrated suppressor and a fixed PSO-1-1 scope. It also has semi-auto and full-auto firing modes. Extended magazines increases its capacity of 10 rounds to 20 rounds. It fires the same "9MM" ammunition as the Beretta or the UMP-9, even though it uses 9x39mm ammunition in real life.
Machine Guns
DP-28
The Degtyaryov DP-28 machine gun appears in the 1.0 release version of the game and can be found as a uncommon loot spawn exclusive to the map, Erangel. It is chambered in "7.62mm" ammunition in a 47-round pan magazine, and can only accept scopes up to a 6X magnification.
M249 SAW
The M249-E2 SAW appears ingame as the "M249", and can only found in crates that are parachuted in, known as "Care Packages." It fires the "5.56MM" ammunition from a 100-round belt box, and can only accept sights and scopes up to 6X as attachments.
Grenades
M67 Frag Grenade
The M67 appears in game simply as the "Frag Grenade".
M18 Smoke Grenade
The M18 smoke grenade appears ingame simply as the "Smoke Grenade". Unlike the actual grenade, the M18 ingame is only available in white smoke.
The Heckler & Koch UMP appeared in the game as "UMP-9", and was chambered for "9mm" ammunition. It can be identified as a 9mm variant by its curved magazine. It could be fitted with foregrips or a laser sight, all muzzle devices and magazine variants, as well as all sights up to the 4x scope. Extended magazines raise the magazine size to 40 cartridges from its original 30. As of the March 2019 Update #27, the UMP-9 was wholly replaced with its .45 ACP brother, the UMP45.
IMI Micro Uzi
The Micro Uzi appears in the game under its proper name, and is chambered for "9mm" ammunition. It can be fitted with all muzzle devices, magazine variants and a stock, which is a unique attachment for the Uzi. Extended magazines raise the magazine size to 35 cartridges from its original 25. In the Season 4.1 Update, it was wholly replaced with its modern incarnation, the IWI Uzi Pro Pistol, allowing it to accept red dot and holographic sights. Despite the presence of an accessory rail below the barrel, the game does not allow lower rail attachments to be used with this weapon.
Mk 2 Frag Grenade
Mk 2 hand grenades appear in the Early Access menu screen, but are not usable ingame.
M26 Frag Grenade
Much like the Mk 2s, M26 hand grenades appear in the Early Access menu screen, but aren't usable in game.