Nightmare
Tier List

S+ Tier
AE-21C
AUG A3 - AP/+10
AK-47 - AP/+10
AK-12 - AP/+10

S Tier
SCAR-H  - +10
ACR - HP/ +10
Jack Carbine - AP/ +10

A Tier
MK-18 - AP/ +10
M4A1 - AP/+10

B Tier
AKS74U - AP/ +10
M4 Carbine - AP/ +10

S+ Tier
Maverick - Incendiary
PPSH-41 - FlamDrum
UMP .45 - AP

S Tier
Jack Carbine - AP/+10
G-21C - AP
Vityaz - AP

A+ Tier
CBJ-MS - AP
MP7A2 - AP/ +10
M1014 - Double Load

A Tier
MP5 - AP

B Tier
Thompson - HP/Drum

S+ Tier
Maverick - Incendiary
Persuader 500 - Drum Mag
Ultimax 100 - HP
HK21 - AP/+10
RPK - Any attachments

S Tier
M1014 - Double Load
MP7A2 - HP/+10
UMP-45 - AP
PPSH-41 - Flam Drum
Wingmaster - Slug
M870 - Flechette

A+ Tier
MP5 - HP
Wingmaster - Slug

A Tier
CBJ-MS - HP

B Tier
Thompson - HP/Drum
G-21C - HP

S+ Tier
ARK-3 - More Mags

S Tier
EBR - More Mags
Lee Enfield - More Mags
Winchester 1873 - More Mags  

A+ Tier
Ruger 10/22 - Rat Shot 
M14  - Drum Mag

A Tier
M1 Carbine - +5 

S+ Tier
Gold Revolver - Speed Loader/Passive Reload (Can be used in all classes)
Revolver - Speed Loader/Passive Reload

S Tier
CZ 75 - MK II
G-18 - Drum Mag
HK USP - Caliber+
M9 - M93R MKII Conversion
Walther - +5

A Tier
A-3000 - Tactical
G17 - Tactical

B Tier
P226 - +5
FNX-9 - +5

C Tier
Makarov PM - Drum Mag
Hi-Point C-9  - Tactical

S+ Tier

Katana: Eclipse Blade -  Ghostwalker - Zweihander - Chainsword


S Tier
Hammer: Merica Flag - Cyber Spear -  Scythe


A Tier
Wrench: Pan - Rubber Chicken - Pipe
Machete


B Tier
Hatchet: Candy Cane

C Tier
Karambit - Scalpel - Hot Dog - M9 Bayonet