There are few problems that can't be solved by the liberal application of high explosives.

If you're trying to take down a heavily armored Troll with a pistol, things are not likely to end well...except for the Troll.
The best way to deal with something like that is...have someone else do it.

This could be your friendly neighborhood Mage, who can Stunbolt that puppy into next week (if you're lucky) or, even better - set his big, heavily armored behind up to take a fall.
While a 40-story drop could work, the kind of fall I mean is...do you have any
other enemies? Do some legwork and find a way to get Big Bad Troll and your other enemies to think that the stuff you're doing is stuff that the people you don't like are doing, and let THEM worry about the Troll.
Then just sit back, record the brawl to watch later (with popcorn, in slow motion), wait until the smoke clears, and pick off any survivors.
Easy peasy.

-Jn-
Everyone's Favorite Vile Fiend