Going to depend on
1. how much background information each side has concerning the other
2. who goes first
If Psylocke knows no more about Crimson than I did, she dies.
If she's aware, though, Betsy can convince Crim that she has already fired her guns, or is even continually firing them and that they are not working.
Note that Psylocke even 20 years ago had the skill for this, using the tactic to thwart Omega Red's lethal "Death Factor".
More recently Betty made Mystique sane in the midst of physically sparring with her, and solo took down a MAJOR named player in the X-verse:
(Don't worry. It took life-saving intervention, but Magneto survived to see another day ...)
