Bigger doesn't always mean strong. The strength of an explosion depends on the energy inside the bomb. We've already seen larger explosive scale in this manga even by fodder battles, but it would never scratch Perfect Susanoo when it can barely destroy huge rocks:
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The scale of Deidara's clay chakra infused bombs were insane as well, yet Sasuke(in Curse seal level2) tanked it:
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Hell even his C0 that seemed too gigantic and powerful had a pitful result in the end:
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Sai uses paper bombs as well with his ink techniques. The scale was enough to catch a great part of the forest, yet it barely scratched Haku's mirrors:
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All this to show how judging the power of an attack by the scale is a mistake. Regardless of the scale, the energy ratio inside a Bijuudama is significantly above that of the paper bombs from GK