Weapons nature and balance

[TBeholder]

• Shotgun
  Shouldn't slugs count as "normal_heavy"? They aren't as easily stopped as smaller bullets.
  And why slugs don't allow "Aimed" mode?
  
• Machinegun
  Isn't it supposed to use bigger cartridges than assault rifle and therefore have greater damage, range and penetration?
  Also, shouldn't they have bad accuracy from hip, but crouching should improve it more than for SMG/AR while crouching (as in, firing from bipod)?
  
• Lasers
  Why all armor is more efficient against lasers than kinetics, even medium (most of which presumably is already AP)? Especially given that even heavy laser is correctly given no penetration at all against objects.
  
• Beams
  Conversely, how resistance to the same high-energy particle beam can possibly have medium values across significantly different types of armor? For charged particles  it's not a random process, it's gradual loss of energy - they either have low enough energy to be completely absorbed by given layer of material, or they pass, and then anything thinner made of material with comparable density will only somewhat slow them down, which won't do much good (as in, a few mm of aluminium can completely stop 10-20 MeV protons, but being hosed with 230-MeV protons instead of 250-MeV isn't a big improvement).