The FN FNP-45 Tactical, called the "FNX45" in game, is one of the .45 semi-automatic handguns in the game. It uses 15 round .45 ACP magazines, and accepts a red-dot sight as well as pistol flashlight. The model appears to be a redone version of the "4-Five .45" taken from ArmA 3, as it even sports the same attachments. The weapon and it's magazines currently only spawn at US Helicopter wrecks, making it one of the rarer sidearms available to players.
AWC Amphibian S Ruger MKII
The AWC Amphibian S Ruger MKII appears ingame as the "Amphibia S", using a standard 10-round .22LR magazine. It is incredibly quiet, being almost undetectable by players beyond very close range. It is intriguing that a very expensive variant of a pistol used by U.S. Navy SEALs appears in the game at all. Like the FNX45, it spawns at US Helicopter Crashsites, however it's magazines can be found at regular wrecks and other military locations.
CZ 75 SP-01 SHADOW
The CZ 75 SP-01 SHADOW appears, known in-game as the "CR75", and is made by "Cheraruska Zbrojovka", an odd spin on the real world CZ company. Like the FNX-45, it accepts the ambiguous "pistol suppressor" (also incorrectly used on the .45 ACP FNP-45) and "pistol flashlight" (that is also used by the FNP-45 and both 1911 variants).
Kimber Warrior
A slightly-modified Kimber Warrior appears ingame as the "1911". Unlike the real Kimber Warrior, the in-game 1911 has a traditional M1911-styled rear sight, and has straight slide serrations rather than angled ones. It takes standard 7-round magazines and can sport a pistol flashlight, due to its rails.
A much rarer engraved variant of the 1911, accurately called the "1911 Engraved", is available as well.
Walther P1
A Walther P1 appears as the "P1 Pistol", and uses 8 round 9x19mm magazines. Unlike most of the other pistols, it does not accept any attachments. It is relatively uncommon in comparison to the Makarov and CR-75.
Thompson Center Arms Contender
A Thompson Center Arms Contender appears as the "LongHorn". The in-game Contender previously had a permanently attached scope until patch 0.57 where the Scope could be detached and placed on the Crossbow. It always spawned with the Scope Attached and could mount a Crossbow Holosight as a close range alternative. It uses .308 Winchester ammunition.
Makarov IJ-70
The Makarov IJ-70 appears as the "Makarov IJ70", and is chambered in .380 Auto. It cannot accept any attachments.
Derringer
The Derringer doesn't seem to be explicitly designed from an actual model, but is rather an amalgamation of many designs. It's chambered for 2 .45 ACP rounds, and comes in 3 varieties. Black, Grey and a stylish Pink.
Orion Flare Gun
An Orion Flare Gun was added to the loot tables in 0.53. While the weapon and it's ammunition currently spawn at paddleboat spawns, it can spawn in any weapon location in Residential or Military Locations. Despite it's description of not being used as a weapon, it makes an ideal last resort against an unsepecting player. It's ammunition is currently bugged where Ejected unfired rounds cannot be reused.
Revolvers
Colt Python
A chrome Colt Python, known as the "Magnum .357" in-game, appears as (currently) the only revolver in the game. The Colt Python is correctly chambered in .357 Magnum, and accepts a speedloader for faster reloading.
Shotguns
Baikal IZH-43
The Baikal IZH-43 appears as the "IZH43", and uses 12 gauge shells. A Sawed-Off IZH-43 can be created using a hacksaw, increasing the recoil and decreasing accuracy but taking up less inventory space. It can be loaded with twin-shell speedloaders.
Baikal MP-133
The Baikal MP-133 appears as the "MP-133 Shotgun", using a 6-round 12 gauge tube. Another variant with pistol grips appears as the (rather long-named) "MP-133 Shotgun with pistol grip", holding 4-rounds instead of the standard variant's 6.
Rifles
M4A1 Carbine
The M4A1 Carbine appears, being the only select-fire weapon as of yet. It is correctly chambered in 5.56x45mm ammo, and features the widest amount of customization available to any weapon (Accepting everything from black and OD Magpul stocks and handgrips, to Aimpoint M68 CompM2 and ACOG sights, as well as bipods and flashlights.) It also has the largest variety of magazines; being the standard 30-round STANAGS, as well as 10, 20, 30 and 40 round Magpul P-Mags (All in fashionable black and fabulous OD green) and two coupled 30 round STANAG mags. As per text on the M4A1's receiver, the rifles in game are manufactured by CMMG Provisions, a company long associated with Bohemia Interactive, who was also responsible for designing the "MX" series appearing in ArmA 3.
Mosin Nagant M91/30
The Mosin Nagant M91/30 appears as the "Mosin 9130". In the early days of DayZ development, the weapon incorrectly uses 7.62x51mm ammo but this was rectified as of 0.55 and the Mosin will now fire the correct 7,62x54mmR. The Mosin-Nagant M91/30 can be equipped with a few attachments, including an M44 Compensator, M91 bayonet, and PU scope. In previous versions a 12x Scope could be attached however this has recently been changed so that only the PU Scope can be attached. The Mosin-Nagant can be spray painted black, green, or a camouflage mix of both.
As of the 0.48 update, the "Mosin 9130" can be cut down into an Obrez, called the "Sawed-Off Mosin 9130" ingame. Similar to the Sawed-Off IZH-43, the Obrez Mosin features saw marks on the barrel and stock, where the rifle has been cut.
SKS
A Yugoslavian SKS M59/66 appears, simply, as the "SKS". It is correctly chambered in 7.62x39mm, and accepts a bayonet as well as PU scope. The SKS, like the Mosin-Nagant, can be spray painted either black, green, or a camouflage mix of the two.
Blaser B95 "Luxor"
The Blaser B95 "Luxor" appears as the "Blaze 95 Double Rifle", chambered in .308 Winchester (Which is one of many calibers the B95 supports). It has a measly two round capacity, but is very accurate even out to 200m. An option to fire both barrels exists by pressing "T" which will fire both barrels in quick succession. The 0.57 patch added the ability to add a Hunting Scope with a x8 magnification.
Ruger 10/22
The Ruger 10/22 is featured, as the "Sporter-22" and manufactured by "Kruger Arms" (a common spin on Ruger-based firearms for copyright issues). It can utilize either the standard 10 round rotary magazine or use a 30 round aftermarket magazine. The 0.57 patch added the ability to mount a x8 Hunting Scope.
FN Trombone
Called the "Trumpet" in-game, it was added in the 0.54 update. Compared to the Ruger 10/22, it does not require a magazine and holds 11, .22 Long Rifle rounds. It can also be disassembled into a more compact form, allowing to be stored inside a backpack. Currently, like some other weapons, it's able to accept an improvised bottle suppressor.
AKM
An AKM rifle appears as the "AKM". It uses 7.62x39mm ammunition, and is compatible with many attachments. Among them are a PSO-1 scope, several handguard replacements, and an interchangeable full-wooden and folding stock (which is not possible in real-life, as a full-stock AKM receiver does not have the necessary modifications to sport a folding stock.) The game's AKM can become an AKMS that is created when the AKM is given a folding stock. Despite the stocks not being interchangeable in real life, the AKM retains its name and the difference is completely aesthetic.
AK-101
An AK-101 appears in-game chambered in 5,56x45mm NATO. It uses its own 5,56mm AK-101 magazines and can only use the bipod and weapon flashlight when the RIS rail handguard is equipped. It can also mount most of the AKM, AK-74 and AKS-74U style stocks in addition to the PSO-1 Scope.
Despite its look it's actually a modified model of the AK-74M, an older model seen in DayZ's development cycle before the AK-74 was officially added. It's located in general military loot, although its ammunition is comparatively rarer than the native 5,45x39mm and the 7,62x39mm.
CZ-527 Carbine
The CZ-527, 7.62x39mm carbine variant, appears as the "CR527 Carbine", manufactured by "Cheraruska Zbrojovka" as the CR75 is. The original model created was the .223 variant, but this was later changed to accommodate gameplay.
AK-74
An AK-74 appears as the "AK74", and uses "5.45mm Rounds". It can mount a bipod and weapon flashlight when the AK Handguard Rail is attached and can fit the PSO-1 Scope.
Rossi R92
A Rossi R92 appears as the "Repeater", using ".357 Rounds" and having an internal capacity of 11 rounds.
AKS-74u
The AKS-74U appears in the game, commonly spawning in military zones. It's chambered for 5.45x39mm. Unlike its bigger brother the AK74, the AKS-74U is incapable of mounting any handguards or the PSO-1 Optic. However, it's small compact size means it can be stowed away inside some of the larger backpacks, making it the ideal backup weapon to a Sniper.
Steyr AUG
Added in 0.51, the Steyr AUG is one of the rarer weapons that spawns at US Helicopter Crash Sites. It features it's unique 1.5x Swarovski Optik. It can take it's own 30 round Steyr AUG Magazines as well as STANAG.
Submachine Guns
Heckler & Koch MP5K
The MP5K appears as the "MP5-K". Although it is found with a PDW-Style stock by default, it does not have the MP5K-PDW styled flash hider and is thus a standard MP5K with the stock attached. The MP5K can also attach a Pistol Suppressor and a Compensator, turning it into an MP5K PDW.
PM-73 RAK
The PM-73 RAK appears as the "PM73 RAK". The PM-73 is a .380 Auto variant of the PM-63, which was included as the developers decided against adding 9x18mm ammunition. It's reputation as one of the game's most rare weapons was rectified with an update that implemented Central Loot Economy. It commonly spawns at police stations and tank wrecks and can take either 15 round or 25 round magazines.
Grenades
Currently, grenades only spawn at helicopter crashsites, however the RGD-5 has a tendancy to spawn at Military Locations at an extremely low chance. They are extremely rare, and are unlikely to be encountered, even by experienced players.
M67 Hand Grenade
An M67 Hand Grenade appears as the "Explosive Grenade". The in-game M67 has an unusually large explosion, more akin to high-level aircraft ordnance, rather than a hand grenade. This is a result of the explosion effect for grenades not being finished, and re-using the explosion of a gas station instead.
M84 Stun Grenade
The M84 stun grenade appears in DayZ as the "Flashbang". Contrasting the regular M67 grenade, the M84 has a very long description explaining it, whereas the M67's simply says "Grenade".
RGD-5 Hand Grenade
The RGD-5 hand grenade appears as the "RDG-5 Explosive Grenade". The RGD-5 is slightly more common than the M67 (though still extremely rare), and has a much shorter fuse.