my simple advice is to :
1. not use a pistol. thats 1 1/2 Kg and the ammo, it's a complete waste of space.
2. save your AP ammo for when the shit gets real, and use only ONE caliber.
i prefer the M16 to the AK (or whatever they are called.); the snipers are great fun but unpractical.
same goes for the late game weapons - i admit they are cool, but they are not as effective.
the bulldog has almost no ammo in the game, and it's awkward to use properly.
the Thunder hits hard, but has too much recoil, bad sights, meh flight trajectory, small mag.
the VAL and Vintorez have bad range, small mags, and while the damage is high (and they are suppressed) the flight trajectory is horrible.
the two top tier 5.56 guns are just so much better, more so in the games where you upgrade them, if not, then the special versions. the bullets fly far, straight, and they have extreme accuracy and low recoil.