Stun Mastery: multiplicative?

Misread, will re-test. I'll go to slimes for negligible def.

Lv2 barrage now, 98%*4 for the last hit, but still doing slightly less than 15k to slimes no-crit. 3840 max range in this test, 3840*(.98)*4 gives 15052, so that part alone is close. Even if I had my charged range and lv1 barrage again, it's still 15k (about 20 damage less in theory than my current setup)... I don't see the 17k anywhere. The most damage I've ever seen myself do is low 60k's, and that includes MW19 and lv2 barrage. Not close to 72k...

Well, I was using an approximation for your base range, which seems to have been off

You should be doing 15k without crit, 24k with crit, and 61k with SE. That fit better?