ORIGINAL: eldeguello
Well, before I look at your results, I will guess it was either the .220 Swift or the .22/250. This guess is based on the results of similar tests run by people like Phil Sharpe, Townsend Whelen, and Harvey Donaldsonwhen they were developing .22-cal. varmint rifles back in the 1930's..... The HV .22 bullets, regardless of type, would often blow hens-egg sized holes through steel plate that even a .30/'06 AP round only made a smear on....
I found this to be true many years ago, when i was doing a lot of bullet testing...
When it came to bigger calibers, the ones that did the most damage (even in T1 steel) were the higher velocity rounds with NP's loaded in them!
DM