GBB/GNB (Gas Blow Back)

GBB/GNB (Gas BlowBack / Gas Non BlowBack)
Next to your assault rifle or sniper rifle, many use a sidearm as backup (Pistol or SMG). You can find these here in the category GBB/GNB (gas blowback / gas non blowback). They are Gas or CO2 powered.
The blowback function gives an extra dimension to realism, that's why you can also find a couple of GBBRs (Gas Blowback Rifles).
Gas/CO2 replica's require more maintanence then a standard AEG, because rubber parts are used to keep it airtight.