I shot 2 young black wolves a few years ago that almost came into our camp while we were making lunch. I used what I had close by. The first one was stopped broadside, and the Federal Fusion 225 gr .338 dropped it in its tracks with a lung shot. the second one made a run for it, and kind of got hit quartering away, from the guts to the front shoulder. It needed a LOT more stitching, but the taxidermist did a good job fixing the mess.
After that, I bought a .243 for wolves, but have only specifically targeted them once more since then, with no luck.