Of course they can wear out, as tree-climber has related, but the problem you are seeing in those CVAs is early life and not unique. I've seen no definitive cure posted for the problem - but CVA warranty service is quite good. I would be curious to know what loads you were shooting in those rifles.

One other area to check, that I think Cayugad might have left out in his good post, is the crown of the bore. It is possible you have damaged the crown by either loading or cleaning technique or perhaps worsened an existing flaw. Crowns are difficult to check in a barrel with a recessed crown but still worth an effort toward inspection. Look for any deviations from uniformity. There are tools made to polish crowns and those alone might cure your rifle's ills.

The "easy load" section at the end of the barrel can be a problem area for accuracy. While you are there anyway, look that over carefully to make sure there are no deposits of material or rough areas. These "QLA like" barrels are handy for sabot users but may not be worth the complications.