If you have the lugs lapped on a bolt action, will the headspace change enough to have the barrel set back??

If not, will lapping the lugs have a noticeable effect on accuracy? Now shooting 1 1/2" groups at 100yds. This is acceptable but would like to tighten up by 50%.

Don't have the big $$$ to spend on a complete accuracy package, but would like to start somewhere and eventually get the action totally worked.

Just wondering if it will be money well spent.

Thanks