Man, you do like long posts, uhm?
Anyway, just because a weapon doesn't have Ares labeled on the side of the barrel, doesn't mean it isn't from a company owned by Ares.
Anyway, some of the companies that design weapons:
Ares: no doubts about it.
Ceska czech company, possibly owned by Saeder-Krupp.
Colt: american company, possibly owned by Ares.
Fichetti: no company exists in RL with this name, but it sounds somewhat italian to me, Saeder-Krupp maybe?
FN: belgian manufacturer, possibly owned by Saeder-Krupp.
Hammerli: swiss manufacturer, possibly owned by Saeder-Krupp or, considering how the Swiss love to remain neutral, it could be an independent manufacturer.
Heckler und Koch: german manufacturer, possibly owned by Saeder-Krupp.
Israel Weapon Industries: Israeli manufacturer, designer of the (in)famous Uzi smg, independent?
Izhevsk: russian manufacturer, best known for their AK series. I couldn't find much about Russia situation, but I will assume it is an independent company for now.
Military Armament Corporation: american military company, designer of Ingram and MAC's SMG's. If we consider that after the USA was desfragmented, one of the major companies might have privatize it, I would bet it would be Ares.
Mitsubishi: they do exist in RL, it is a huge conglomerate. Perhaps one of the AAA Japanese corps bought it and expanded their niche.
Mossberg: american manufacturer, possibly owned by Ares.
PJSS: couldn't find it in RL, independent?
Ranger Arms: american manufacturer, possibly owned by Ares.
Raecor: The only Raecor company that I could find in RL was a medicine company.
Remington: american company, possibly owned by Ares.
Ruger: american company, possibly owned by Ares.
Steyr: austrian company, possibly owned by Saeder-Krupp.
Streetline Special: no company name attached to it, unknown.
Yamaha: they do exist in RL, but are a vehicle manufacturer. Perhaps one of the AAA Japanese corps bought it and expanded their niche.
Ok, by my accounts, Ares is possibly the winner by a head against Saeder-Krupp.