A modular linear striker has a firing pin assembly, an axial spring and a housing. The firing pin assembly includes a firing pin and a reset spring and may also include a separate slider. The firing pin has a resting position, a cocked position and a firing position. The reset spring biases the firing pin back in its resting position. When the slider is incorporated into the firing pin assembly, the axial spring biases the slider forward with a preloaded force. The housing surrounds the firing pin assembly and the axial spring. The housing has a notched section between its front face and its body section which fits within a setting in the firearm frame. The notched section engages the fitting in the firearm frame so that the modular linear striker is arranged in the proper position and orientation within the frame.