Found in light zone armory or from the corpse of MTF/Chaos unit, armor will not just save you from bullets, but also allow you to wield more ammo, medicals, weapons and grenades.
For now, all armor possesses a box model with an ominous gaze of Him. The only visual difference between those armors is that they have unique icons on top, which is the only thing capable of controlling Him from breaking out of this vile containment. Armor takes up one inventory slot.
Armor will reduce bullet damage depending on its Helmet/Vest efficacy, but SCPs will still deal same damage with or without armor.
There are 3 armor sets for now:
Light armor:
Helmet Efficacy - 45%
Vest Efficacy - 40%
Has no Movement speed, Stamina Usage debuff
Ammo Limits: +30 9x19mm(60 total)
Item Limits: +1 Firearms(2 total)
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Combat armor:
Helmet Efficacy - 80%
Vest Efficacy - 65%
Has no Movement speed debuff, but +20% Stamina Usage
Ammo Limits: +90 9x19mm(120 total), +80 5.56x45mm(120 total), +80 7.62x39mm(120 total), +30 .44 Mag(48 total), +40 12/70 Buckshot(54 total)
Item Limits: +1 Firearms(2 total), +1 Grenades(3 total)
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Heavy armor:
Helmet Efficacy - 80%
Vest Efficacy - 80%
-10% Movement speed, +20% Stamina Usage
Ammo Limits: +170 9x19mm(120 total), +160 5.56x45mm(120 total), +160 7.62x39mm(120 total), +50 .44 Mag(48 total), +60 12/70 Buckshot(54 total)
Item Limits: +2 Firearms(3 total), +2 Grenades(4 total), +1 Medical Items(4 total)

The obvious part of the new beta version, it adds up new guns, reworks old guns, makes 'em sеxier, cooler.
You can change fire modes in your revolver by pressing middle mouse button for faster fire rate with worse recoil or vice versa;
You can unreload your gun by holding R;
You can inspect your gun by pressing I.
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--PISTOLS--
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.44 Revolver
Ammo: 6/6 .44 Mag
Damage: 36,5;
Firerate: 240 RPM;
Length: 14 in;
Weight: 4,7 lb;
Hip Accuracy / ADS Accuracy:
-ATTACHMENTS-
Barrels: Extended(15% slower Draw Speed, +10% Damage bonus, 50% more accurate), Short(-10% damage bonus, +30% less accurate, +70% faster Draw Speed);
Magazines: Armor Piercing rounds(4 bullets in mag, +30% Penetration bonus, 20% more accurate), Extended Mag size(40% slower firerate, 8 bullets in mag);
Stocks: One and only(20% slower Draw Speed, 60% more accurate, 35% less recoil);
Sights: Collimator sight(5% slower Draw Speed, 5% faster aiming down sight) and sniper scope.
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COM-18
Ammo: 16/16 9x19mm
Damage: 20,2;
Firerate: 360 RPM;
Length: 8 in;
Weight: 1.6 lb;
Hip Accuracy / ADS Accuracy:
-ATTACHMENTS-
Barrels: Suppressor(25% slower Draw Speed, shots are 60% less loud), Extended(25% slower Draw Speed, 35% slower aiming down sight movement speed, 15% Damage bonus, 10% Penetration bonus);
Misc.: Laser Dot Sight(10% slower Draw Speed, Hip firing is 70% more accurate), Flashlight(10% slower Draw Speed, emits light, duh)
Sights: Collimator sight(5% slower Draw Speed, 5% faster aiming down sight).
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COM-15
Ammo: 12/12 9x19mm
Damage: 19,6;
Firerate: 300 RPM;
Length: 7 in;
Weight: 1.4 lb;
Hip Accuracy / ADS Accuracy:
-ATTACHMENTS-
Barrels: Suppressor(25% slower Draw Speed, shots are 60% less loud, 10% more accurate);
Misc.: Flashlight(10% slower Draw Speed, emits light, duh);
Magazines: Extended mag size(10% slower Draw Speed, 17 bullets in mag).
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--SMG--
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FSP-9
Ammo: 30/31 9x19mm
Damage: 21,1;
Firerate: 630RPM;
Length: 18 in;
Weight: 5,4 lb;
Hip Accuracy / ADS Accuracy:
.
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CrossVec
Ammo: 40/40 9x19mm
Damage: 20,9;
Firerate: 720RPM;
Length: 24 in;
Weight: 5,8 lb;
Hip Accuracy / ADS Accuracy:
.
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--HEAVY WEAPONRY--
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MTF-E11-SR
Ammo: 40/40 556x45mm
Damage: 24,6;
Firerate: 570 RPM;
Length: 34 in;
Weight: 6,9 lb;
Hip Accuracy / ADS Accuracy:
-ATTACHMENTS-
Bodies: Rifle Body(15% slower Firerate, 15% slower Draw Speed, 7,5% Damage bonus, 15% Penetration Bonus, 35% more Accurate);
Barrels: Extended(15% slower Draw Speed, +10% Damage bonus, 50% more accurate), Short(-10% damage bonus, +30% less accurate, +70% faster Draw Speed);
Magazines: Armor Piercing magazine(30 bullets in mag, +15% Penetration bonus), Hollow Point magazine(30 bullets in mag, -40% Penetration bonus, +17% Damage bonus), Extended magazine(reload takes +2 seconds, 65 bullets in mag);
Underbarrel: Foregrip(10% slower aiming down sight movement speed, 5% slower Draw Speed, 15% less Recoil), Laser Dot Sight(5% slower Draw Speed, Hip firing is 50% more accurate);
Stocks: Lightweight Stock(15% more Recoil, 20% faster Draw Speed), Recoil Reducing Stock(15% slower Draw Speed, 20% less Recoil);
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AK
Ammo: 30/30 762x39mm
Damage: 27,5;
Firerate: 498 RPM;
Length: 34 in;
Weight: 9,9 lb;
Hip Accuracy / ADS Accuracy:
-ATTACHMENTS-
Bodies: Rifle Body(15% slower Firerate, 15% slower Draw Speed, 7,5% Damage bonus, 15% Penetration Bonus, 35% more Accurate);
Barrels: Extended(15% slower Draw Speed, +10% Damage bonus, 50% more accurate), Short(-10% damage bonus, +30% less accurate, +70% faster Draw Speed);
Magazines: Armor Piercing magazine(30 bullets in mag, +15% Penetration bonus), Hollow Point magazine(30 bullets in mag, -40% Penetration bonus, +17% Damage bonus), Extended magazine(reload takes +2 seconds, 65 bullets in mag);
Underbarrel: Foregrip(10% slower aiming down sight movement speed, 5% slower Draw Speed, 15% less Recoil), Laser Dot Sight(5% slower Draw Speed, Hip firing is 50% more accurate);
Stocks: Lightweight Stock(15% more Recoil, 20% faster Draw Speed), Recoil Reducing Stock(15% slower Draw Speed, 20% less Recoil);
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SHOTGUN
Ammo: 14/14 12ga
Damage: 85,2;
Firerate: 141 RPM;
Length: 29 in;
Weight: 8,7 lb;
Hip Accuracy / ADS Accuracy:
-ATTACHMENTS-
Barrels: Extended(15% slower Draw Speed, +10% Penetration bonus, 10% more accurate), Shotgun Choke(20% bigger Spread, spread is very predictable),;
Misc.: Ammo Counter(5% slower Draw Speed, shows ammo), Laser Dot Sight(Hip Firing is 50% more accurate), Flashlight(5% slower Draw Speed, emits light, duh).
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Logicer
Ammo: 100/100 762x39mm
Damage: 26,9;
Firerate: 660 RPM;
Length: 45 in;
Weight: 24,9 lb;
Hip Accuracy / ADS Accuracy:
-ATTACHMENTS-
Barrels: Flash hider(10% slower Draw Speed), Muzzlebrake(10% slower Draw Speed, gunshots are 20% louder, 30% less Recoil), Short(-5% Damage bonus, -5% Penetration bonus, +30% faster Draw Speed);
Underbarrel: Foregrip(10% slower aiming down sight movement speed, 10% slower Draw Speed, 20% less Recoil), Flashlight(emits light, duh), Laser Dot Sight(Hip firing is 50% more accurate);
Sights: Dot Sight(Aiming Down Sight is 5% faster), Ammo Sight(10% slower aiming down sight movement speed, Aiming Down Sight is 20% Faster, ability to see your ammo count), Nightvision Scope(25% slower aiming down sight movement speed, Aiming Down Sight is 5% Faster).
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So far, you can make a sniper rifle out of revolver, make anti-scp Logicer out of AK/E11, and Shotgun will be very powerful against SCP-939 if you put a laser sight and extended barrel on it.

All human classes will have 100HP
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MTF
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Facility Guard
Light Armor
Guard Access Card
FSP-9
Medkit
Radio
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PRIVATE
Radio
Private Access Card
FSP-9
Combat armor
Medkit
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SPECIALIST (Escaped Scientist)
Radio
Sergeant Access Card
E-11
Combat Armor
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SERGEANT
Radio
Sergeant Access Card
E-11
Combat Armor
Medkit
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CAPTAIN
Radio
Captain Access Card
E-11
Heavy Armor
Adrenaline
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CHAOS INSURGENCY
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RIFLEMAN
Medkit
Painkiller
Combat Armor
Chaos Insurgency AccessDevice
AK
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CONSCRIPT (Escaped D-Class)
Medkit
Painkiller
Combat Armor
Chaos Insurgency AccessDevice
AK
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REPRESSOR
Medkit
Painkiller
Combat Armor
Chaos Insurgency AccessDevice
.44 Revolver
Shotgun
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MARAUDER
Medkit
Adrenaline
Combat Armor
Chaos Insurgency AccessDevice
Logicer

Lots of items got reworked model/animations like flashlight, radio, scp-207,scp-268, scp-500 or painkiller(you will open the bottle as soon as you equip it), medkit, adrenaline, MicroHID;
Upon wearing scp-268, new purple overlay will be seen;
Flashlight got reworked light;
You can throw items by pressing T, it will allow you to break glass by throwing heavy enough item into it, unlocking doors on distance by throwing appropriate keycard on the keypad;
Weapon Stations do not require Weapon Tablets anymore, as there are no such things;
Disarmers are removed because disarming will be reworked;
Weapon stations can be seen in the Heavy Zone corridors;
Great fuсking optimization;
Light Zone Armory will have 1 Heavy armor, 2 Combat armors, 1 FSP, 2 CrossVecs, 4 and 6 9x19mm mags and 2 COM-18s. There will also be 2 Weapon Stations;
Tesla gates have new animations/sounds;
Medical cabinets will also have an adrenaline inside.

If I forgot to write about something, feel free to threaten me in comments about it.