Chrome lined barrel, and barrel wear?

How much more longevity would a chrome lined barrel have over one that isn't? And how much, if any wear differences is there between a stainless steel barrel and a regular steel barrel? My example would be any sort of rifle that fires an intermediate sized round 7.62x39, .223 ect. I've also heard that... show more How much more longevity would a chrome lined barrel have over one that isn't? And how much, if any wear differences is there between a stainless steel barrel and a regular steel barrel? My example would be any sort of rifle that fires an intermediate sized round 7.62x39, .223 ect. I've also heard that chrome lined barrels lose accuracy, is this true? And is it possible to chrome line older, heavily used firearms that still work well? Or can you chrome line mil-surps that were never used if one wanted too?