[@Crimmy]

The force of the blast is just from my rudimentary knowledge of how explosions kill people is by over pressuring the area. Apparently death can be caused by so much as a 4 pounds per square inch increase in pressure. Limbs can be blown off at ten. Trying to look into this now because I wasn't really expecting to go into more detail then there's a big explosion that destroys the mech as a downside. seriously if you give me a solid number Id just use that. 

but for the sake of argument let's say 100m. Assuming that 20m is like an equivalent to 6ft relative to the size of the mechs, and I am definitely assuming a lot here, then it'd be an equivalent of 30 feet to be safe, which is what, a move action in D&D. that might work. again you can just give me a number.

I assure you it'll be as armored as it needs to be. I'm not going to just randomly detonate this to ruin someone's day.

Still didn't answer my question about whether or not that means everything else is approved?

Off to go research protection from overpressure.