Mammillaria I.D. Help. (with flower pics)

I had trouble identifying this cactus when I got it so I decided to wait until it flowered. I have a few idea's but would rather see what others think first.

mammillaria karwinskiana I'd guess.

Yeah that's what I was thinking. I was pretty convinced it was M. Magnimamma until it went to flower and they didn't turn out pink. If anyone else has any suggestions I'd love to here but for now I'm pretty content to stick with that.