(its requirements)Look at the requirements for the items you are comparing:
Microwave Ray (Boiling Blood) - Eng 75, Level 14
JackHammer (Earthquake) - Eng 85, Level 18
Water Cannon (Tsunami) - Eng 85, Level 18
So, based on your Level and Engineering, you should expect different results from these. Also, the ray gun is a one target gadget, the others are multi-target, which tend to do less damage, per target. I've had the ray do over 100 damage (seems to do more damage at long range than close up), but if the other items ever did that, they would be way to powerful.
Tools for Wizardry(r) 7