Thread: Genuine question

A lot of cartridges share a common bolt face

.243 7mm08 .308 common

.223 300blk common

There will be plenty more. Usually wikipedia gives a good family history of a cartridge its parentage and its dimensions. If a cartridge shares a common bolt face and common magazine length with what you want to change it to, then changing the barrel will be 90-95% of the work.
There may be smaller bits and pieces required like changing the length of the ejection plunger or alterations to the feed ramp as now you are feeding a differently shaped projectile and possible ejecting a different length/weight case.

Going to a cartridge that requires a different bolt face dimension is possible depending on what the change is too, but it involves much more hassle. As others have said above, easier to buy a new rifle. The difference in cost for the bare rifle wont be much more or less than the barrel and the work.