I would start to guess at 65cm for the length. For another exercise in mathematics you could find the center of each tube at the breech and measure the distance between the centers. Then find the center of the tubes at the muzzle and measure that distance. Then with the length along the top rib and with the diameter of each tube at the muzzle as well as inside wall thickness, project the inside of each tube until they intersect using similar triangles. This is all based on the thought that the tubes are concentric.
Kind Regards,
Raimey
rse
Holy crap....whaaa...
happy holidays,
tim
