Start with the thinnest shim, (.002") and install, then check to see how your bolt closes.
As long as it continues to close normally, continue to add shims .001" at a time, stacking as necessary.
(Example = .003", .004", .005", Stack .002"+.004"=.006" .003"+.004"=.007" etc.)
When you have installed enough shims that the bolt just begins to be hard to close,
remove .001" so it closes normally or just (ever-so) slightly tighter than normal.
If you have to force or put undue stress on your bolt to close it, you should reduce the number of shims.
The Bolt Play between the Bolt Halves was designed into the assembly by Mr. Ruger
We are only concerned with the Bolt-Breech lock-up fit, and there you can have anywhere from
<.001" ( perfect) to >.005"+ which will definitely affect accuracy."
A minimum of clearance should be maintained, do not put undue stress on bolt
by shimming under .001" as it is unnecessary!
Sounds like .oo4 in yours is good.