Intriguing. Let's try to make some more informed guesses based on this.
Note that weapon efficiency is flux / damage = flux/shot / (damage/shot) = flux/second / (damage/second), and Alex said this is pretty good.
And Alex said the weapon fires pretty slowly, so we can make some guesses at the shot(s) / second value.
So we get damage / shot = damage/second / (shots/second) = damage/second * flux / damage / (shots / second * flux / damage)
= flux / second / (shots / second * flux/damage).
If the weapon is pretty flux efficient then its flux efficiency is probably between 0.1 and 1.
And if the weapon fires pretty slowly then let's say it fires something like from 1 time every 1 second (heavy blaster rate) to once every 20 seconds (half of antimatter blaster rate).
Now we can table the results for 150 / (shots / second * flux / damage) to get a table of what the weapon's damage per shot would be. Note that 6 shots per min is AMB firing rate, 30 shots per min is mining blaster firing rate, and 60 shots per min is heavy blaster firing rate.
Shots
per Flux efficiency
min 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
3 30000 15000 10000 7500 6000 5000 4286 3750 3333 3000
6 15000 7500 5000 3750 3000 2500 2143 1875 1667 1500
9 10000 5000 3333 2500 2000 1667 1429 1250 1111 1000
12 7500 3750 2500 1875 1500 1250 1071 937 833 750
15 6000 3000 2000 1500 1200 1000 857 750 667 600
18 5000 2500 1667 1250 1000 833 714 625 556 500
21 4286 2143 1429 1071 857 714 612 536 476 429
24 3750 1875 1250 937 750 625 536 469 417 375
27 3333 1667 1111 833 667 556 476 417 370 333
30 3000 1500 1000 750 600 500 429 375 333 300
33 2727 1364 909 682 545 455 390 341 303 273
36 2500 1250 833 625 500 417 357 312 278 250
39 2308 1154 769 577 462 385 330 288 256 231
42 2143 1071 714 536 429 357 306 268 238 214
45 2000 1000 667 500 400 333 286 250 222 200
48 1875 937 625 469 375 312 268 234 208 188
51 1765 882 588 441 353 294 252 221 196 176
54 1667 833 556 417 333 278 238 208 185 167
57 1579 789 526 395 316 263 226 197 175 158
60 1500 750 500 375 300 250 214 188 167 150