The correct priming method for large-diameter AN-FO charges has long been a subject of controversy. Axial priming, multiple point priming with small charges, thermal priming, and shock priming are techniques which have been advocated. The correct location, size, shape, and formulation of primer have been debated. Various researchers, including the Bureau of Mines, have performed studies which clarify the situation. This paper brings together conclusions reached by different studies and makes specific recommendations to the operator.