A combustion chamber liner for a rocket propulsion system, comprising: a combustion chamber liner body 124 extending between a first and second end; a combustion chamber liner internal wall 102 defined by the combustion chamber liner body 124, the combustion chamber liner internal wall 102 defining a combustion area cavity 122 extending between the first and second end; a combustion chamber liner external wall 104 defined by the combustion chamber liner body 124, the combustion chamber liner external wall 104 being opposite the internal wall 102; an inlet port 110 defined by the combustion chamber liner body 124 at the first end; a nozzle exit port 112 defined by the combustion chamber liner body 124 at the second end; a throat portion 114 defined by a portion of the combustion chamber liner body 124 between the first and second end; and a plurality of spiral cooling channels 116 defined by the combustion chamber liner external wall with each spiral cooling channel 116 having a cooling channel wall thickness, the plurality of spiral cooling channels 116 extending between the first and second ends, with each of the plurality of spiral cooling channel 116 comprising a first chamfer at a first cooling channel end and a second chamfer at a second cooling channel end, wherein each cooling channel has a first decreasing wall thickness defined by the first chamfer that gradually decreases along the length of the cooling channel from the first cooling channel end to a minimum cooling channel wall thickness at the throat portion 114 and a second decreasing wall thickness defined by the second chamfer that gradually decreases along the length of each cooling channel from the second cooling channel end to a minimum cooling channel wall thickness at the throat portion 114. a combustion chamber liner body 124 extending between a first and second end; a combustion chamber liner internal wall 102 defined by the combustion chamber liner body 124, the combustion chamber liner internal wall 102 defining a combustion area cavity 122 extending between the first and second end; a combustion chamber liner external wall 104 defined by the combustion chamber liner body 124, the combustion chamber liner external wall 104 being opposite the internal wall 102; an inlet port 110 defined by the combustion chamber liner body 124 at the first end; a nozzle exit port 112 defined by the combustion chamber liner body 124 at the second end; a throat portion 114 defined by a portion of the combustion chamber liner body 124 between the first and second end; and a plurality of spiral cooling channels 116 defined by the combustion chamber liner external wall with each spiral cooling channel 116 having a cooling channel wall thickness, the plurality of spiral cooling channels 116 extending between the first and second ends, with each of the plurality of spiral cooling channel 116 comprising a first chamfer at a first cooling channel end and a second chamfer at a second cooling channel end, wherein each cooling channel has a first decreasing wall thickness defined by the first chamfer that gradually decreases along the length of the cooling channel from the first cooling channel end to a minimum cooling channel wall thickness at the throat portion 114 and a second decreasing wall thickness defined by the second chamfer that gradually decreases along the length of each cooling channel from the second cooling channel end to a minimum cooling channel wall thickness at the throat portion 114.