The correct answer is "maybe". S&W used both single and dual spring setups in the compact 40 & 45s'. Best way to tell is how tight is your spring to your guide rod. The dual spring setup requires a thinner rod for the smaller spring to work with, some converted early guns also had a bushing that is used in the front of the slide for the smaller rod to run in. The dual springs are only available through S&W, the single can be had from them or Wolff.