My first thought would be that if the best load in the rifle is 2" (and that implies others are worse) that there is something up with the rifle. We have already heard a good starting list, Bedding, screws not binding, screws properly torqued, trigger reasonable, both lugs bearing, rings correctly mounted and tight, scope good. Crown etc. If the issue is one of these items a new tube will be just as frustrating.
If its floated you might try some upward pressure for a laugh.
That said I have a number of rebarreled Rugers and with a good tube and no issues they are all capable of sub MOA type accuracy, but that seems to be true or nearly enough not to matter for factory MKII's and Hawkeyes. From the perspective of a sporter the Ruger action is really no better or worse a platform than most. Its not what I would build a precision target or LR rifle from ( nor a Lightweight rig), but if rugged CRF actions float your boat its not so bad a choice.
My opinion that as a sporter, what an aftermarket tube mostly buys isn't necessarily a leap forward in accuracy( unless your original tube was buggered), but your pick of chambering, throating, contour, length and lack of fouling/ease of cleaning.
