B2 Chrome barrel accuracy

[browningautorifle]

I saw a Vid on the M60 E5 with a composite barrel that they claimed was good for 15000 rounds

Those are likely the Stellite barrels, a composition of four metals and extremely hard, they were bored to accept an insert of this material that was the liner only. The gasses forced in at the edges would cause rust underneath so they were discontinued. Otherwise, the next best thing was the way the Russians had used nickle lined barrels. They apparently lasted for ever...and cost a gazillion $ to produce.