We had to euthanize a bird today. We used a pistol style pump pellet gun to the back of the head. He never knew it was coming and it was instant. We didn't process him because he was skinny and had a prolapsed vent (vent gleet) we tried to medicate first for quite awhile. Anyway, we were happy with the pellet gun method.
Thank you for letting us know about the pellet gun working well for you.