Steel tops and gun powder are not the best mix.
I suppose if one felt compelled for some reason to pour his
powder out into piles on his steel table rather than keeping it
in the original cans and then strike hard glancing blows next
to the piles with a steel hammer it could cause a problem.
But I thought only black powder ignited with a spark and
smokeless required a flame? My bench top is way too cluttered
to strike a glancing blow with anything but it does have a
sprinkling of spilled powder.
After I finished drilling and tapping all of my mounting holes
I gave the steel top a heavy coat of paint via the trusty old
spray can. Then I cut a piece from 3/16" plywood to fit the
top plate and mounted my tools atop it. Not from fear of
sparks, just a better looking surface to work on.