An apparatus for cutting a wellbore tubular, comprising: a receptacle engaging with a mandrel; an upper section and a lower section in the receptacle, the upper and the lower sections mating at a juncture plane defined by a plane transverse to a longitudinal axis of the well bore tubular; wherein each section includes a support plate (44;50) having a passage, a ring-shaped liner (48;54) positioned adjacent to the support plate (44;50) and an energetic material (46;52) disposed between the support plate (44;50) and the liner (48;54); an initiator having a shaft traversing the upper section and the lower section, wherein the initiator includes at least one radial bore that is orthogonal to the longitudinal axis and is bisected by the juncture plane; and a fastener engaging the shaft to compressively secure the upper section with the lower section, the fastener further having a pedestal portion that separates the lower section from the receptacle; a gap separating the liners (48;54) from an interior surface of the receptacle, wherein the gap allows fluid communication between a space between the lower section and a lower inner surface of the receptacle and a jet forming region, and wherein the gap and the liners (48;54) are configured such that, after detonation of the energetic material (46;52): the liners (48;54) expand radially outward to create a seal between the liners (48;54) and the interior surface of the receptacle, wherein the seal prevents a gas formed by the energetic material (46;52) from entering the jet forming region; and the gas formed by the energetic material (46;52) is allowed to flow into a first space between the lower section and a lower inner surface of the receptacle and flow into a second space between the upper section and an upper inner surface of the receptacle. a receptacle engaging with a mandrel; an upper section and a lower section in the receptacle, the upper and the lower sections mating at a juncture plane defined by a plane transverse to a longitudinal axis of the well bore tubular; wherein each section includes a support plate (44;50) having a passage, a ring-shaped liner (48;54) positioned adjacent to the support plate (44;50) and an energetic material (46;52) disposed between the support plate (44;50) and the liner (48;54); an initiator having a shaft traversing the upper section and the lower section, wherein the initiator includes at least one radial bore that is orthogonal to the longitudinal axis and is bisected by the juncture plane; and a fastener engaging the shaft to compressively secure the upper section with the lower section, the fastener further having a pedestal portion that separates the lower section from the receptacle; a gap separating the liners (48;54) from an interior surface of the receptacle, wherein the gap allows fluid communication between a space between the lower section and a lower inner surface of the receptacle and a jet forming region, and wherein the gap and the liners (48;54) are configured such that, after detonation of the energetic material (46;52): the liners (48;54) expand radially outward to create a seal between the liners (48;54) and the interior surface of the receptacle, wherein the seal prevents a gas formed by the energetic material (46;52) from entering the jet forming region; and the gas formed by the energetic material (46;52) is allowed to flow into a first space between the lower section and a lower inner surface of the receptacle and flow into a second space between the upper section and an upper inner surface of the receptacle. the liners (48;54) expand radially outward to create a seal between the liners (48;54) and the interior surface of the receptacle, wherein the seal prevents a gas formed by the energetic material (46;52) from entering the jet forming region; and the gas formed by the energetic material (46;52) is allowed to flow into a first space between the lower section and a lower inner surface of the receptacle and flow into a second space between the upper section and an upper inner surface of the receptacle.