//ammo system changer. 0 is T+T2 style, 1 is T+T style, 2 is bullet-hose classic blockland style
RTB_registerPref("Ammo System","Tier+Tactical Ammo","$Pref::Server::TTAmmo","int 0 2","Script_GamePreferences",0,0,1);
so you'll want mode 1
perhaps you should do this, Bushido
RTB_registerPref("Ammo System","Tier+Tactical Ammo","$Pref::Server::TTAmmo","list Normal 0 Classic 1 None 2","Script_GamePreferences",0,0,1);