I just shot my dads 375 holland and holland. Sako L61R. My target was a large piece of 1/2 inch steel, slanted downward at 30 degrees to deflect the rounds downward. I fired at 30 yards from behind a tree stump and the whole the 225 grain softpoint left is as big as a quarter the hole way through. A 3006 fired at this target gets 1/3 of the way into the steel, leaves a bump in the back, and bounces back through the target holder.

If you have anecdotes or tech info about bullet penetration,please share them here.

I thhink I've found my ideal moose rifle.

the british used the same and other calibers to pierce  the steel shields the german snipers were using to approach allied trenches during world war1 and take shots with relative impunity..... for a while.