You have your tabbing all off.
Code:
AddAmmo = Round
PresetName = Round RT
ParticleCount = 2
Particle = MOPixel
PresetName = Particle RT
Mass = .3
RestThreshold = 500
LifeTime = 500
Sharpness = 700
HitsMOs = 1
GetsHitByMOs = 0
Color = Color
R = 20
G = 30
B = 200
Atom = Atom
Material = Material
CopyOf = Bullet Metal
TrailColor = Color
R = 200
G = 20
B = 20
TrailLength = 70
Shell = MOSParticle
CopyOf = Casing
FireVelocity = 500
ShellVelocity = 8
Separation = 0