I love shooting water jugs! Like you said, it's not super-scientific FBI jello...but I get them for free and they are fun to blow up.
I test any ammo brand I may carry in gallon water jugs. I don't really have any specific performance levels I'm looking for. But if a round won't expand in water it probably won't expand in something trying to hurt me.
I've tested both those rounds you did....also in a 4" 686...not surprisingly got identical results