AgGaSe 2 and AgGa 1− x In x Se 2 single crystals have been grown by the horizontal gradient freeze technique directly along the phase-matching orientation required for frequency-doubling the output of a 9.27 μm CO 2 laser. Samples for second harmonic generation exceeding 55 mm in length have been fabricated from 19 mm-diameter boules with minimal waste. Low-loss AgGaSe 2 samples (after annealing in Ag 2Se) generated over 3 W of 4.6 μm output at external efficiencies of 26%. AgGa 1− x In x Se 2 crystals were grown with In concentrations between x=0.37 and 0.42, and were free of the Ga 2Se 3-rich precipitates that normally plague as-grown AgGaSe 2. Non-critically phase-matched second harmonic generation was successfully demonstrated in the sample grown from a melt with x=0.42.