u/Beginning-Ad-7107

Swedish tank destroyer with a 155mm gun and an oscillating turret.

Type 2 105/39 “Betonfeindlich”, translated to “hostile to concrete” or “anti concrete” (very literal name, I used a translator so excuse me if i’m wrong) was an interwar attempt by alternative Germany to build a mobile anti fortifications vehicle.
Weighing 9.67t (not intentional) it has a top speed of 18km/h while having at max 20mm of armor, most of the weight comes from the massive 105mm naval cannon making it very back heavy. Originally built as an anti bunker platform, it had excellent anti armor capability even late into the war, the naval origins gave it high muzzle velocity (around 655m/s) and so good penetration. It is the first ever mass produced vehicle to be used as a tank destroyer (but it is still classified as an assault gun).
But of course due to the design and the huge barrel, it had terrible depression and being open top doesn’t help with survivability. The driver is completely deaf and the mediocre engine made it unreliable on sloped terrain (as if it could even aimed at the enemy). The recoil was reported to be so aggressive that the whole vehicle could flip over when aimed at the sides.
The Betonfeindlich survived till the end of the war and was even heavily modified in other nations serving for another decade.