The game features a significant amount of weapon customization options, including receivers, rails, stocks, handguards, sights, grips, barrels, etc.
Handguns
The pistols available in-game have threaded barrels for mounting muzzle attachments.
Glock 17
The Glock 17 simply appears as the "G17" and costs 5000 in-game currency.
MasterPiece Arms MPA930DMG
The MasterPiece Arms MPA930DMG was added to the game, referred to as the "DMG Nine-Milli". It is depicted as fully-automatic rather than semi-automatic.
PL-14 Lebedev
The PL-14 prototype of the Lebedev pistol is available in the game. It is incorrectly described as using 9x18mm Makarov ammunition as opposed to 9x19mm Parabellum. The Lebedev costs 6000 in-game currency to unlock, making it the most expensive pistol so far.
PR-15 Ragun Prototype
The PR-15 Ragun is a pistol option in the game, named "Ragun". The in-game weapon is modeled after 3D printed mock-up prototype designs made by FB "Łucznik" Radom first shown in 2012. It's the default secondary pistol as of the 0.2 patch.
Submachine Guns
PM-98
The PM-98 Glauberyt is available, simply named "Glauberyt" in the Early Access release version. The description erroneously states that it is chambered in 9x18mm Makarov; this type of ammunition was used by the earlier PM-84 in reality. As of the 0.2 patch, it's unlocked by default.
PP-19-01 "Vityaz-SN"
The PP-19-01 Vityaz-SN appears. In the Early Access version, it is named as the Vityaz. The Vityaz is available for 12500 in-game currency.
SIG-Sauer MPX SBR
The SIG-Sauer MPX SBR is featured in the game as the "SIG", and is intended to pass for a full-auto MPX submachine gun. It's available for 12500 in-game currency.
Rifles
AK-12
The 2014 prototype of the AK-12 appears, chambered in in 7.62x39mm. It is referred to as the "AK-15", but this designation in reality was given to the 7.62x39mm AK-12 model from 2016 onwards; as such, that labeling isn't appropriate for in the in-game version. The AK-12 is currently the cheapest assault rifle available for unlock, at 15000 in-game currency.
AK-Alfa
A conceptual rifle jointly developed between CAA of Israel and Kalashnikov USA, the AK-Alfa is featured in the game. It's available for 18000 in-game currency, making it one of the two most expensive assault rifles to unlock.
Beryl M762
The Beryl M762 was referred simply as the Beryl in beta builds before it was indexed as the Beryl 762. It's available for 16500 in-game currency.
Daewoo K2C1
The Daewoo K2C1 is scheduled to be added to the game.
FN SCAR-H
The FN SCAR-H was added with the 0.3 patch. It's the first battle rifle in-game, and only fires in semi-automatic mode.
The Heckler & Koch HK416 first appeared in the Gamescom 2018 build of the game. Initially, it was called "G38" (which is the designation of the HK416 A5 variant in German service), but the name was later changed to "M416". It is fitted with a Geissele SMR handguard, Magpul BAD lever, and a ridiculously oversized A5 buttstock. It's available for 18000 in-game currency, making it one of two most expensive assault rifles to unlock.
First appearing in the game's PTE server, the MSBS-5.56B Grot was added with the 0.2 patch as the "MSBS-B". It is chambered in .300 AAC Blackout, and costs 16500 in-game currency.
MSBS-5.56K Grot
The MSBS-5.56K, referred simply to as the "MSBS", is the default assault rifle as of the 0.2 patch.
"VEPR"
The "VEPR" is a fully-automatic AK-pattern rifle that was added to the game. It consists of a Vepr-12 shotgun's receiver (even having "12x76" markings above the magwell), along with a Saiga 308 style gas block and front sight, and a railed handguard. The shape of the magazine looks like that of a 5.56x45mm AK magazine.
Shotguns
Remington 870
A Remington 870 in a tactical configuration is available in the game. It is referred to as the MCS variant, but it isn't actually modeled after this one, mainly due to the different pumping handle. It features long, medium, and short barrel customization options. It's available for 16000 in-game currency.
Vepr-12
The Vepr-12 is available in the Early Access version of the game, and costs 16000 in-game currency.
Sniper Rifles
Haenel RS9
The Haenel RS9, designated G29 in German service, appears as one of the sniper rifles in the Early Access version of the game. As of the 0.2 patch, it's unlocked by default.
ORSIS T-5000
The ORSIS T-5000 appears in-game. In the earliest release footage, it was named the T-5000, while the Early Access version names it "Tochnost", which refers to a militarized version of the OSRIS T-5000. It is available for 20000 in-game currency.
WKW Wilk
The WKW Wilk, known as "Tor" in Polish service, appears to be one sniper rifle in the Early Access version of the game. It's the most expensive sniper rifles to unlock, costing 26000 in-game currency.