bellydeep,

Heat is the major factor in barrel erosion, eroding the steel, which eventually causes cracking of the surface. Even if chrome-lined, the chrome can crack too, which actually accelerates erosion because cracks in surface of steel keep the super-heated gas circulating in that area, rather than blowing down the bore.

I did this with one of the J.C. Higgins rifles mentioned by natman, a .270 Winchester. Like his rifle, mine was very accurate, but eventually the accuracy started deteriorating. My bore-scope revealed that the surface throat cracked just like it would without chrome-plating. It may have taken longer, but I don't know.

One thing that can help when the cracking starts is a few fire-lapping rounds, which smooth out the cracks and slow the erosion. I did that with the .270 but it didn't help as much as it had in other rifles, so I rebarreled it to 6.5x55.

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