Gas bleed assemblies for use with firearms are described. An example gas bleed assembly for use with a firearm having a barrel includes a gas cylinder that defines at least one gas outlet to be fluidly coupled to a bore of a barrel. The gas cylinder is substantially fixed relative to the barrel. Additionally the example gas bleed assembly includes a holding fixture that is substantially fixed relative to a housing having a front edge. The holding fixture interacts with the at least one gas outlet. A temperature induced variation of geometry of the barrel changes a position of the gas cylinder relative to the holding fixture and wherein a pressure acting within the gas cylinder is associated with the position of the at least one gas outlet relative to the holding fixture.