Almost all weapons are rebalanced. They are now much more realistic, altough im not sure with the groupings of automatic weapons, as i am not sure how the configuration works in that section. Weapon damage is increased, some weight stats are increased or decreased, shotguns accuracy is increased, weapon range set to real life effective range, muzzle velocity also set with real data, along with fire rate and mag size. 

Pistols. 9 mm pistols like the Beretta, Fort, Hi Power, PM, PB, and Walther have great fire rate and medium accuracy but short range. They are better suited as a defensive mag dumper, when you need to kill a target up close quickly. .45 caliber pistols like 1911, P220, and USP have moderate fire rate, medium+ accuracy, short+ range, and more damage, but their magazine size and lower fire rate meant that its less effective for some situations. Altough it is a compromise between the larger calibers and 9 mm pistols, and a compromise of their weakness too. Larger calibers like the Desert Eagle and it's variant is a heavy hitting sidearm with medium range, excellent accuracy and great damage. But the magazine size is small, and fire rate is very slow. Pistols have firing range from 50-200 meters depending on the gun.

Submachineguns/PDWs like MP-5 and AKS-74U are now a worthy considerations to the pistols. They are much heavier, but their performance are considerably superior at the cost of space and weight of course. MP-5 can fire further than pistols, while AKS-74U have almost rifle-class range but heavier and fires slower than MP-5. Firing range between 200-400 meters depending on the weapon.

Assault Rifles can be considered the weapon for the game now. Some assault rifles reach 500 meters of firing range, and some other have more than that. A variety of firing rate, damage and accuracy. Some are rapid firing suppressive weapon, some can be a marksmen rifle. 5.45 rifles deals a bit damage but have lesser range. 5.56 deals lower than 5.45, but goes further. 9 mm rifles deals excellent damage, but rather short range for a rifle. Firing range of 400-800 meters depending on the gun.

Sniper Rifles. Long range domination, capable of up to 800 meters with extreme precision, and potentially kills with one hit. SVD have the longest range but slower firing. SVU have lesser range, but good fire rate. Vintorez have the shortest range and lower damage but is very quiet and fast fire rate. All sniper rifles have excellent groupings. Firing range of 400-800 meters depending on the weapon.

Explosives are lethal. RGD-5 have 350 shrapnels traveling at 700 m/s, 10 meters blast radius and 20 meters shrapnel radius. F-1 have 290 shrapnels at 700 m/s, 15 meters blast radius and 30 meters shrapnel radius. Rifle mounted grenades are less lethal than these grenades with effective blast radius of less than 18 meters. RPG-7 is the most powerful but very rare, 700 meters range with 40 meters blast radius. The RG-6 is basically semi automatic version of rifle grenades with almost identical stats.

Shotguns. BM16 have the widest spread, Winchester 1300 medium spread, and SPAS tight spread. Effective range is about 50 meters, and they are excellent against mutants.

Barrel length of each firearm affects its accuracy and damage, along with the ammo type. So.. if you happen to know a specific technical data about a specific firearm, you probably know what are you looking for between these weapons.