Keep in mind the MANY PMC's forbid the use of non company owned weapons -- so most will be issued a G19 and a M4A1 (think BW, 3C, Dyn etc. -- or on some contracts a M9 and M4).
Very few companies these days issue an Ak, at least amongst Expat Security companies.
Anyone running a 9mm long gun needs their head examined - PERIOD - during the early days in both Afghan and Iraq the MP-5 was a status choice used by idiots that keep re-living Princess Gate and had some sort of mistaken beleif they where 22 SAS...
Bringing a pistol or pistol calibre round to a gun fight as a primary weapon is a woeful lack of planning, and is a recipie for being D-E-A-D.
FWIW on my team there are 4 Short FAL's and two long's