06/24/2018 (Sun) 21:36:16
Its looks like nothing special. I see a 4x4 which has been routed for the scrap pipe barrel to fit in nice and snug (likely to lessen the intensity of the kick for a more snug fit). I see a few small rusty brackets to mount it to the upper receiver. Typical homemade bolt chamber but I can't tell what caliber its made for. Whatever it is I assume its for single shot loading.