Commercially available hyperspectral cameras are useful for remote sensing, but in most cases snapshot imaging is difficult due to the need for scanning. The coded aperture snapshot spectral imager (CASSI) has been proposed to simultaneously acquire a target scene's spatial and spectral dimensional data, employing a refractive prism as a disperser. This paper proposes a CASSI-based technique using a generally available diffraction grating of a Ronchi ruling and blazed grating and its improvement using the undispersed zeroth-order light. The feasibility and performance of the proposed technique are experimentally validated, and the grating parameters are identified.