@9 There should be an entry in scripts/hudanimations_tf.txt that has to do with low ammo pulsing, just clear out the text between the first pair of braces in that section and it should go away.
event HudLowAmmoPulse
{
Animate HudWeaponLowAmmoImage Alpha "255" Linear 0.0 0.0
Animate HudWeaponLowAmmoImage Alpha "0" Linear 0.125 0.075
RunEvent HudLowAmmoPulseLoop 0.25
}
to
event HudLowAmmoPulse
{
}
If that somehow breaks TF2, just put the RunEvent line back.