Until now, the steampunk world is depicted as Victorian with airships and early WW1-era weapons.
But what if we make something better. Can steampunk weapons be (relatively) as advanced as modern ones?
Can a steam tank as good as Tiger? Can a steampunk sniper rifle fire .50 cal projectiles like the Barrett?
Can a stealth aircraft breaks the sound barrier using somekind of advanced steampunk engine?
Thank you in advance!
The assumption of "steampunk" genre is that relatively small steam engines could, with further development, become equivalent in efficiency to gasoline and diesel engines OTL, at least WWII era ones.
In Real Life, NO.
But most other "steampunk" tropes gleefully violate the laws of phsyics (iron-clad dirigibles, for instance), so if it's your universe, you can violate the laws of physics as you please.
If you stick to "real world" physics,
1) Power to weight ratio sez 'nope'.
2) .50 caliber is a size. That's a half-inch projectile. Considering there were actually .50 caliber sniper rifles in the American Civil War, I am going with yes. But the question you meant to ask, whether or not the .50 caliber BMG cartridge can be produced in a Steampunk timeline, yes. Smokeless powder is not a problem, it was starting to come into use in the late 19th century. Prior to WWI, the round didn't really exist because there wasn't a NEED for such a cartridge. It was invented to poke holes in WWI tanks.
3) Ummm. . . steam-powered heavier than air flight fails due to power-to-weight ratios. Calculations of the characteristics of radar cross-section and how to minimize them would not be impaired in steampunk universe, and the creation of radar-absorbant materials is more impacted by chemistry than mechanical engineering changes.