Here’s the Feinstein’s amendment

the Attorney General may deny the
transfer of a firearm if the Attorney General determines,
based on the totality of the circumstances, that the
transferee represents a threat to public safety based on a
reasonable suspicion that the transferee is engaged, or has
been engaged, in conduct constituting, in preparation for, in
aid of, or related to terrorism, or providing material
support or resources therefor. For purposes of sections
922(t)(1), (2), (5), and (6) and 925A of title 18, United
States Code, and section 103(g) of Public Law 103-159 (18
U.S.C. 922 note), a denial by the Attorney General pursuant
to this provision shall be treated as equivalent to a
determination that receipt of a firearm would violate section
(g) or (n) of section 922 of title 18, United States Code, or
State law. A denial described in this section shall be
subject to the remedial procedures set forth in section
103(g) of Public Law 103-159 (18 U.S.C. 922 note) and the
intended transferee may pursue a remedy for an erroneous
denial of a firearm under section 925A of title 18, United
States Code. Notwithstanding any other provision of law, such
remedial procedures and judicial review shall be subject to
procedures that may be developed by the Attorney General to
prevent the unauthorized disclosure of information that
reasonably could be expected to result in damage to national
security or ongoing law enforcement operations, including but
not limited to procedures for submission of information to
the court ex parte as appropriate, consistent with due
process. The Attorney General shall establish, within the
amounts appropriated, procedures to ensure that, if an
individual who is, or within the previous 5 years has been,
under investigation for conduct related to a Federal crime of
terrorism, as defined in section 2332b(g)(5) of title 18,
United States Code, attempts to purchase a firearm, the
Attorney General or a designee of the Attorney General shall
be promptly notified of the attempted purchase.

And here we have the Cornyn amendment (Poison Pill?):

At the end add the following:
Sec. 5__. Hereafter, the Attorney General shall establish
a process by which–
(1) the Attorney General and Federal, State, and local law
enforcement are immediately notified, as appropriate, of any
request to transfer a firearm or explosive to a person who
is, or within the previous 5 years was, investigated as a
known or suspected terrorist;
(2) the Attorney General may delay the transfer of the
firearm or explosive for a period not to exceed 3 business
days and file an emergency petition in a court of competent
jurisdiction to prevent the transfer of the firearm or
explosive, and such emergency petition and subsequent hearing
shall receive the highest possible priority on the docket of
the court of competent jurisdiction and be subject to the
Classified Information Procedures Act (18 U.S.C. App.);
(3) the transferee receives actual notice of the hearing
and is provided with an opportunity to participate with
counsel and the emergency petition shall be granted if the
court finds that there is probable cause to believe that the
transferee has committed, conspired to commit, attempted to
commit, or will commit an act of terrorism, and if the
petition is denied, the Government shall be responsible for
all reasonable costs and attorneys’ fees;
(4) the Attorney General may arrest and detain the
transferee for whom an emergency petition has been filed
where probable cause exists to believe that the individual
has committed, conspired to commit, or attempted to commit an
act of terrorism; and
(5) the Director of the Federal Bureau of Investigation
annually reviews and certifies the identities of known or
suspected terrorists under this section and the
appropriateness of such designation.