Does the .50 hyper require head shims to run 30% nitro? I went from 20% to 30% today and coincidentally fried my engine. I reset the needles to break in settings and that didn't keep it from happening.

You may need to either reduce compression or lengthen a tuned exhaust system or both. Going to higher nitro fuels means that the engine needs a lower compression ratio or retarded timing to operate correctly.

Any advice on the best way to "reduce compression" since the owner's manual doesn't mention the need to?

You add head gaskets to reduce compression. Usually adding one more is enough.