The Woolly Mammoth were supposed to be larger than African elephants I believe. Also as they lived in an ice age and near the polar caps in addition to their hair I would guess they would have layers of thick fat for insulation.

It has been hypothized that the early hunters the mamnmoth hunters hunted them by the use of group strategy eg using firebrands to scare the mammoth and drive them over cliffs.

Also by spearing them from several different sides but I guess this tactic proved fatal for some.

I would use a similar tactic and choose two firearms. For myself a nice .500 NE, double of course. For my friend, let's call him "Mike"

, a four bore single, most important equipped with a sling.

Using group tactics I would fire two shots from the .500 and then "Mike" could let rip with the blackpowder single 4-bore. "Mike" being encumbered by the slung 35 lb rifle and the cloud of smoke would provide a nice diversion and smoke screen for me to escape.

Modern equipment, prehistoric tactics.

I would return with Ayla (the blonde who looks like Darryl Hannah) and the rest of of the tribe later in the day to claim the meat and we would celebrate "Mike's" bravery and sacrifice for the good of the tribe.