Code:
shieldBlastDamageProtection_180 How much protection a shield has against an explosion. 0.0 is none, 1.0 is full. For explosions within a 180-degree arc of the shield.
shieldBlastDamageProtection_120 How much protection a shield has against an explosion. 0.0 is none, 1.0 is full. For explosions within a 120-degree arc of the shield.
shieldBlastDamageProtection_60 How much protection a shield has against an explosion. 0.0 is none, 1.0 is full. For explosions within a 60-degree arc of the shield.
shieldBlastDamageProtection_30 How much protection a shield has against an explosion. 0.0 is none, 1.0 is full. For explosions within a 30-degree arc of the shield.
LESS THAN A MIN!!
Edit:
I dont know if that's for riots, but try this:
perk_blastShield "65"