While searching for Blueprints recently, I ran across drawings for the M16 Government Profile barrel. I was ecstatic and instantly opened my CAD program and started to draw it to scale. However, when I got to the threads on the front and rear I quickly concluded that my system for drawing thread patterns must be wrong. The Muzzle threads called for 28 T.P.I. , which I did and when I was done the angle of the threads seamed to be incorrect. According to the American Machinist Handbook these threads should be 60 degree’s apart as in a V pattern. Instead they ended up being 114 degree’s apart. What the Hell am I doing wrong? I drew up the Major Diameter as being .4989 as the prints showed and the Pitch Diameter as being .4757 as shown. I divided 1’’ by 28 and it came out to .03571428 and made that my standard between threads. How is this wrong when drawing out to a full inch? If I could get this down right it would benefit the Gunco community greatly for my drawings are spot-on except for this. Thanks for any help provided!!!