It seems to depend on the timeline when you actually play the mission. One playthrough I was early in the game at level 6 and it took forever to damage it enough to stop it. Another playthrough I was late in the game at level 42 and one blast from a legendary shotgun crippled it.
Well since i'm friends with choomba Delamain, i did not do hurt his cubs none, but if i'd find myself in such a situation - there is always Caesar's ride (i let him have the money, but something gotta teach the boy to get to his grips, so the car it was). And i don't mean ramming a delamain with it - why ruin the paint. No, i mean the fact that i always keep an HMG or few in the trunk.
Need to blow something up in style? Heavy Machine Gun is the way. Preferably with a thin Body = 3 lady V. Like this: