kh971 wrote: Try to use shims made out of a hardwood perferably oak, they will not compress as badly as some of the softer woods like pine. The shims they sell at hardware stores are made for shimming out doors and windows and may not be a hardwood, if you can put a good indention in it with your fingernail, then you might not want to use it. It will just compress over time a small amount with that much weight on it. My 2 cents.
Thanks for the advice.I actually got some shims from a contractor at work.They are used in retail buildings to shim the displays which are made of metal.I believe they are made from some type of hard plastic compound,but they should work well.Shrinkage should not be an issue.