The term 'single shot' can refer to a firearm that is designed to fire only one round of ammunition at a time. In this context, the crossword solutions for the term are 'STILL' (5 letters) and 'PELLET' (6 letters). A STILL is an apparatus used to distill liquid mixtures by heating to selectively boil and then cooling to condense the vapor. A PELLET is a small, round, compressed piece of material, such as a bullet or a seed.