REALLY reluctant to report this as I've found it very useful, but sometimes when firing a charged alchamer shot all the bullets hit and deal damage simultaneously. So, with a 4*, it would do one charge damage and 4 normal damage to it at the same time.
I can confirm this with my Magma Driver as well. Yesterday, I did a one-hit kill with a jelly in Tier 3, Stone Grove. And jellies are all "meh, elemental dmg, watevs" in terms of resistance.