The response of the EJ299-33plastic scintillator to energetic charged nuclear particles ranging from isotopes of hydrogen to carbon-12 has been analyzed in terms of Birks' semi-empirical approach over the wide range of particle energies from 2 to 20 AMeV. It was found that while the original two-parameter scaling involving Birks' composite quenching parameter kB and an overall conversion efficiency parameter S may be applicable to select sets of particles, a more universal fit would still require individual scintillation efficiencies Sx for individual particle species and more than just one value of the composite Birks'constant kB.