An experimental investigation was made of the spectral and temporal characteristics of an electron-beam-controlled atmospheric-pressure pulse CO laser with an uncooled active mixture. The output radiation energy was 40-50 J and the stimulated emission occurred in vibrational bands from 9 yields 8 to 15 yields 14. The intensity of the radiation due to the 11 yields 10 transition was considerably less than the intensities of the neighboring vibrational bands. A qualitative explanation of the experimental results was based on the partial overlap of vibrational-rotational lines of the CO molecule due to collisional (impact) broadening. A comparison was made with calculations.