Frank De Haas in his excellent book "Bolt Action Rifles" expanded 3rd edition on page 175 states the following when discussing the Brno ZKK action:-

" The action is of all steel construction. The one piece receiver is a forging, very nicely machined on every surface. The 602 is probably the only forged magnum-length Mauser action made anywhere in the world today (at the time of writing), something that ought to make custom rifle builders sit up and take notice."

Later on page 179 when discussing the Metal Finish on the ZKK receiver he states:-

"The Brno ZKK receiver has an unusual finish. It seems to have been heavily sand blasted. The surface has a matte finish that is greyish in color, contrasting with the well-polished blued barrel and the bright bolt and extractor: the effect is quite pleasing."

So yes, I was a little confused at Homers comments about investment casting.