Acme Gun Drill Inserts are manufactured from thru-hardened tool steel and heat treated to 61-65 RC for longer life. The I.D., O.D., and the face of GDI Bushings are ground concentric and square within .0002″ T.I.R.
Inserts are stocked in standard drill sizes only. Special I.D. sizes and special materials (ie. Carbide or Titanium Nitride coating) are available to meet your requirements.