[en] The Los Alamos free electron (FEL) laser oscillator has successfully operated over a wavelength range from 9 to 11 μm with a peak output power of 5 MW and an average output power of 6 kW over a 70-μs pulse length. The FEL is driven by a conventional rf linear accelerator operating at 1.3 GHz with a nominal energy of 20 MeV. Particularly important parts of the beamline are the electron gun, the subharmonic and fundamental-bunching systems, the accelerator, the feedback controllers, the steering and focusing systems, the Cherenkov radiators used as beam-position monitors, and the slow and fast deflectors used with the diagnostic spectrometer at the exit of the beamline. We will discuss problems and present the performance of these components. 10 references, 12 figures, 2 tables