I will make the fullest possible list of weapons here that I can. I will add to this list as things go along:

 

From Vanilla ArmA 2:

M16A4/M4(numerous variants)

AK107(numerous variants)

AK47/74(numerous variants)

Saiga

M82

DMR(Match Grade M14/M1A)

RPG-7

RPG-22

FGM-148

AT-4

SMAW

Mk12 SPR

 

From FFAA Weapons Addon:

HK G36

HK G36 EOTech

HK AG36

HK AG36 ACOG

M82 .50 Cal

Glock 17

USP

USP Silenced

P226

HK MP5A5

HK MP5PDW

HK MP510A3

MG3

MG4

MG4 ACOG

FN FAL(numerous variants)

P90

Steyr AUG

Cetme(numerous variants)