Ft Pounds are dependant on several factors, including projectile weight. To try to put a limit on how many can be produced using black powder is a bit ridiculous.
What for instance would be the foot pounds produced by an 1860's era 25 pounder black powder cannon.
To make it a bit more relative & limit it to shoulder fire sporting guns how many were delivered by the old 8 & 4 bore black powder rifles, some of which burned as much as 16 drams of powder.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra