The internal ribs in the cylinder serve to stiffen the housing while reducing wall thickness and excess weight. 

The thickest wall sections are 120 mils; the thinnest wall sections are 40 mils. 

Surface  flaws and internal porosity in the housing are not permitted, because they would reduce the strength and stiffness and lead to imperfections on the chrome-plated exterior.

The housing needs to have controlled wall thickness and uniform metal fill for structural integrity and rigidity.

The dimensional tolerances on mating surfaces are +/-1.5 mils. General tolerances are +/- 2 mils.