[Poohbah]

IIRC, the Feds only had a search warrant, not an arrest warrant.

In this case, there was probable cause for an arrest warrant (including this jackass saying on ham radio that he intended to kill President Bush).

[El Gato]

IIRC, the Feds only had a search warrant, not an arrest warrant.

You recall incorrectly. from here, where you can also read the warrent application, which like this one apparently did, contained lots of information on perfectly legal practices and possessions.

Federal arrest warrant for VWH case number W93-17m (for Vernon Wayne Howell aka David Koresh) was issued in believe that he was in unlawful possession of an unregistered destructive device in violation of 26 USC.

Federal Search Warrant Case Number W93-15M (for Mount Carmel Center) was issued on the probable cause to believe that unregistered machineguns and destructive devices were being concealed in violation of both 18 and 26 USC.

If you don't like the credibility of this site, check out this law journal article by Kopel and Blackman, which also indicates that both an arrest and a search warrant issued: