I have a question concerning modern chrome lined barrels. It stems from a recent situation where through a series of odd events that have nothing to with this question but nevertheless led to me purchasing a JSE Surplus upper with a 1:7 Wilson Arms barrel (non chrome lined). I wasn't exactly happy about this but I ended up with PSA Magpul edition lower with a PSA LPK married to the above named upper for $580....so not a terrible deal for a pretty solid rifle. I've never even thought about buying an AR15 that wasn't chrome lined because of the better durability, easier cleaning and corrosion resistance I often hear about as opposed to non-chrome lined barrels. Then in an attempt to talk myself out of spending another $200 for a good CL barrel I got to thinking about all the older battle rifles I often see around like the M1 Garand or Mosin's or the later M14's none of which to my knowledge were chrome lined but I still often see them all these years later putting holes through holes. To my knowledge corrosive ammo was also used a lot back then as well. I know for a fact some of those rifles had an amazing amount of rounds through them but yet even without the chrome lining they are still going strong. How can this be if non chrome lined barrels are only good for 5,000 rds like I saw on one sight? 10,000 rounds on another sight. I've read so many different numbers it makes my head spin. I see these decades old battle rifles still going strong and it makes me wonder how important it really is to have a CL barrel or how close it is to a sort of marketing gimmick or easy upsell opportunity. Don't get me wrong I know that CL barrels do have more positives than a non CL barrel and this will probably be the only non CL barrel I will ever own on AR15 but the question still stands. If a CL barrel is so much more durable than a non CL barrel how do people account for the number of high round count WW2 era barrels still going strong? Different manufacturing back then? Different barrel steel back then? Am I missing something or way off base somewhere? Thanks in advance for any replies.