Also there are cameras contemporary to some already deadly firearms (late 19th/early 20th century at a guess). You'd think at the very least a musket would work, or more likely a bolt-action rifle.

My headcannon is that wizard society is so fascist that they just find it too horrifyingly distasteful to use muggle technology (even against Voldermort himself), but also it's why they try so hard to stay hidden because deep down they know they stand no chance against anything resembling a modern muggle army, despite their claims of superiority. I mean, even if Hogwarts itself is protected against technology, an artillery shell is hardly technologically advanced and could be fired from tens of km away.