Dangit I was just going to post the 220 Swift as my guess but you already posted the answer. I talked to the guy at the rifle range here one time and he said by far the most damaging cartridges for the metal silhouette targets were the high velocity .22's and other similar cartidges (like 6mm's pushing light bullets at high speed).

My guess for the second part is the 22-250.

I think bullet construction should be mentioned in this post, though, since you are talking about penetration. I'd bet all of the cartidges would have punched through your metal plate if you had chosen a bullet constructed to penetrate deeper than simple soft points.