If it shoots tweaking the loading procedures is definitely the least expensive option. If it is really off I would set back the barrel so factory or rounds from other rifles would work in it. As someone posted I would do a chamber cast and compare it to the Wylde or Nato chamber.

If it needs a new chamber the AI or .222 Magnum would clean it up even more or the 6mmx47 version is another choice. Also de-grease the bolt and maybe upgrade the firing pin spring with something like a Wolf spring.

"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli