We describe the practical performance of a pulsed mirrorless far-infrared gas laser pumped by a TEA CO2laser. The system is designed to serve as a high-power source for experiments in far-infrared nonlinear optics and saturation spectroscopy of solids. Out of numerous candidates, 11 gases were selected for a careful survey: CH3F,13CH3F, NH3, D2O, D218O, D2S, HDS, CH3Cl, CH3Br, CH3I, and CH3CN. With an available pump energy of up to 10 J, a total of 203 far-infrared lines with pulse energies up to 12 mJ were found, covering the wavelength range from 42 μm to 1.2 mm. 78 of these lines had not been observed before. The position of further 39 lines is at variance with former literature reports.