composite material of low carbon steel case,middle layer of porous bronze filled with tfe resin and a fine lead powder,an overlay of tfe lead mixture; 3 holes drilled thru csk 82 deg plus or minus 2 deg and located 26 deg 30 minutes center to center from the middle hole; hole dia 0.1860 in. min,0.2090 in. max; thickness 0.1180 in. min,0.1200 in. max;length 59 deg of a circle plus or minus o deg 15 minutes with a radius of 6.4375 in. general characteristics item description