Short answer: Yes, except that the police gave permission and actually claimed to be in possession of the weapons used in her presentation.
Brian Weiss, a spokesman for Mrs. Feinstein, told The Washington Times,
that, "The weapons were under Washington MPD possession the entire
time." He said that the office "coordinated with the department" and the
U.S. Capitol Police.
A spokesman for the Capitol Police, Officer Shennell S. Antrobus,
responded two hours later that his department "helped the transfer
within the building" of the firearms, which were then "in possession of
law enforcement there." He would not say what agency was overseeing the
contraband weapons, nor who authorized breaking the city's assault
weapons ban. It is unclear if any law enforcement agency has the power
to overturn the city's firearms ordinances on its own.
If the weapons were supposedly in possession of the police at all times, and if Feinstein asked for and received permission to use them in her presentation, isn't that an admission of unprofessional political bias on the part of the police?
Also, it's important to dispose of the Constitutional question here. The relevant clause reads:
...shall in all Cases, except Treason, Felony, and Breach of the Peace, be privileged from Arrest
during their attendance at the Session of their Respective Houses, and
in going to and from the same; and for any Speech or Debate in either
House, they shall not be questioned in any other Place.