Looks like 1/2" steel? Assuming your are an alright shot and that is roughly 4" group you were around 400 yards give or take. .338 Lupua or .50 Barret possibly? Or you are a crappy shot and its a .300 Win mag at closer range. Then again, it could be soft steel instead of hardened plate in which a .308 could do that at close enough range. If it's a .408 CheyTac you suck for the simple fact that you got to shoot one and Modern Warfare 2 is as close as I will likely ever get to doing so.
I guess we could play this game all day with so many variables, you should pony up and tell us what you shot and at what distance to humor me.
