"Beta" means that most sounds are from trailers. Obviosly they never intended to be in the game.
"Style" means that some sounds never been in trailers (sniper rifle and m4).
Sounds from:
Pistol - many trailers (pm sound from Arma 2)
Pump shotgun - trailers 3 and 4 (applied to combat shotgun as well; saiga and many sniper rifles sound ftom Arma 2)
Uzi - Playboy X traier (think it was pistol sound mistakenly applied to uzi)
Ak47 - trailers 3 and 4 (took directly from trailer 4)
SMG - trailer 3 (GTA SA sound)
M4 and sniper rifle sounds are also taken from Arma 2.