Where do you get the idea that a .45 acp penetrates auto body panels better than a 9mm?
That's not my experience, and I've shot a lot of old cars and car parts in my day (one of my favorite shooting spots was an old junkyard).
And, for that matter, what's this about a "truck gun needs to penetrate a truck" in the first place?
Does a home defense gun need to penetrate your home?
Does a trench gun need to be able to penetrate earthworks and piles of sandbags?
That's not my experience, and I've shot a lot of old cars and car parts in my day (one of my favorite shooting spots was an old junkyard).
And, for that matter, what's this about a "truck gun needs to penetrate a truck" in the first place?
Does a home defense gun need to penetrate your home?
Does a trench gun need to be able to penetrate earthworks and piles of sandbags?