Which weapons are bolstered by which skills?

Solution 1:

The following abilities will affect all weapons:

Leadership (when Aced)
Hard Boiled (when Aced)
Overkill (when Aced)

The Mag Plus skill in tier 6 of the Technician tree increases magazine size for all weapons that do not have a fixed magazine size. This basically means "all weapons" excluding the Bronco (it's a revolver...) and the Mosconi 12G (it's a double barrel shotgun...).

In addition to the above, each class of weapons gets additional bonuses as follows;

Pistols

Pistols are affected by the abilities Equilibrium, Gunslinger, Leadership and (excluding the STRYK 18c) Sharpshooter. The pistols in game are as follows;

Chimano 88
Crosskill
Bronco .44
Bernetti 9
STRYK 18c
Deagle

All pistols are secondary weapons. Pistols fitted with silencers (the Bronco .44 cannot be fitted with a silencer) also pick up bonuses from Silent Killer and The Professional.

Shotguns

Shotguns are affected by the abilities Shot Impact, Shotgun CQB, Hard Boiled, Overkill and Sharpshooter. The shotguns in game are as follows;

Reinfeld 880
IZHMA 12G
Mosconi 12G
Locomotive 12G

All shotguns except the Locomotive 12G are primary weapons. It is possible to silence all of the shotguns apart from the Mosconi 12G, and doing so will pick up bonuses from Silent Killer and The Professional.

Submachine Guns

Submachine guns get bonuses from SMG Specialist, which can be aced to provide further bonuses. The submachine guns in game are as follows;

Mark 10
Compact-5
Para
CMP
Krinkov
Kobus 90

Submachine guns are secondary weapons. They can also be fitted with silencers allowing them to pick up bonuses from Silent Killer and The Professional.

Assault Rifles

Assault rifles are affected by the abilities Kilmer, Rifleman and Sharpshooter when aced. The M308 rifle is considered a single shot assault rifle due to its semi automatic nature. This means the M308 rifle picks up bonuses from Sharpshooter to reduce spread, in addition to the aced bonus.

The assault rifles in game are as follows;

AMCAR
AK
CAR-4
UAR
JP36
AK .762
M308
AK5
AMR-16

Assault rifles are primary weapons and they can be fitted with silencers, allowing them to pick up bonuses from Silent Killer and The Professional.