A handful of explosives, as well as the rules on explosive charges, and some explosive munitions, reference the "Burst" trait, as if it where similar (but distinct from) the "Blast" trait. Does anyone know how this works?
It is probably a mistake
On p. 75 of the core rulebook, "burst" is carefully defined as a fire mode for automatic weapons. On p. 127, the various explosives are defined in the table as having particular "blast" ratings, then the descriptive text on the same page switches to increasing the (non-existent) "burst" rating if the amount of explosive is doubled (or not for pocket nukes). I see no reasonable alternative to treating the p. 127 "burst" entries as meaning "blast" - bigger explosive charges will have an increased "blast" radius, but will not be firing short "bursts" of bullets.