How often will you use the shears after this particular job? If I were only cutting the drum I'd just use a manual handsaw with a metal cutting blade. It'll take some time and effort, for sure, but you might have better control too.
This is pretty nifty, and similar to something I have:
Pit Beeatch for Team Munchkin
Avatar by Northwest BBQ
"...In nature, there are predators. I believe the common denominator of the universe is not harmony, but chaos, hostility and murder..." Werner Herzog