To explain these ideal conditions. The explosive damage can be so great thanks to the target bonus. Consider this, in Another Alchemist in an orb room you decided to go in an orb frenzy and unleash all of them. That's about 6-7 enemies in play per orb so we'll be seeing 20 monsters at an easy reach for r1 Crash Shot radius of 700 (better than windmill but lower than fireball). If you can hit a 250% fragmentation damage, then the explosive damage to the target will be 250% x 20 which is 5000%, which is probably overkill to the target. A critical would be 5000% x 2.5 letting us see a 12500% multiplier on the poor enemy and if you had a campfire enhanced arrow, that's another 1.5 multiplied therefore we see 18750%
With my ranged damage of 300, that looks like 187.5 x 300 which can grant 56250 damage on that enemy given the right number of enemies caught in the fragmentation and the situation.