i have worked with a fair deal of 300 and 400 series stainless. it doesnt require "better machine tools", only different cutting inserts. it work hardens quicker and chip/swarf formation doesnt occur as readily compared to chrome moly. dont take this as it being harder to machine, its only different. on a manual machine a good machinist can work just as accurately and nearly as fast with stainless as he could with chrome moly or most other alloys. with cnc machines, there is almost no difference. the cost of tooling up for stainless only requires changing the speed and feed rates of the machines and then using different inserts. thats it. any cost after that is from material, finishing and markup.

i have heard the rumors that its more accurate, i personally dont buy it if all else is equal. chrome moly has a edge in heat resistance and abrasion resistance (against hard materials) but 416 stainless has greater lubricity properties. hardness can be equal if both are tempered to the same rockwell but 4140 can be tempered alot harder without becoming overly brittle unless 416c or 416v stainless is used. if you dont care about the technical stuff then just think about it as buying less or more rust resistance because most of the real world qualities are equal. personally id take stainless any day but im not passing up a properly blued rifle.