Even for suspected terrorists they need a warrant....or when dealing with foreign terrorists in the US and dealing with FISA they still need a FISA order, but when it is a US citizen they claim is a terrorist, they will still need a FISA warrant at the least.Nothing in the law that provides for that. Collector status does not entitle them to search... However, establishing probable cause to search, in this day and age, is trivial. Simply call you a suspected terrorist and search all they want... after all once they uncover your arsenal of bolt action mosin nagants and mausers (AKA high powered military rifles and sniper weapons) you'll be vilified to the point of no return. Heaven forbid you own more than one black rifle.
Mark
The Bush administration abused FISA and in my opinion committed numerous criminal acts under the guise of presidential powers due to a claim Congroess gave gave ambiguous authority shortly after 9/11 (not the Patriot Act), but just because they conducted warrantless wiretaps and possibly searches (using NSLs IIRC) does not mean they did so legally or Constitutionally.
If they abused FISA to search your home without a warrant by simply claiming you to be a terrorist, then they are facing jail time and there is a financial award in the statute you must be paid.