The LM4 PTR bolt carrier comes with the carrier key installed and will fit all LM4 PTR Series rifles, including the LM4 PTR standard, LM4C PTR, and LM4 RIS PTR, as well as the new LM4 KeyMod line. Please note that this does not come with the metal piston stop, part 36. The piston stop is sold separately and can be found in the link below:
n
n
n
nhttps://kwausa.com/product/lm4-ptr-bolt-carrier-piston-stop/