Here's a wolf I shot in 06. His skull went 17 8/16". 22-250 absolutely flattened him. Unfortunately his hide was mangy.
Here's a big one we trapped in 08. I haven't measured the skull from him, nor have I from any that we have trapped. Some day I should just for curiousity sake.
That was a good day. We got three on one set. Best thing was my daughter was there to share in the experience. She's my good luck charm on the line. Every time she has come out with me we have taken at least one wolf.