The germans tried the curved gun with an attachment called Krummlauf during ww2. It would break after just a couple of magazines being fired. https://en.wikipedia.org/wiki/Krummlauf
Not sure how you would build one of those without the stress of the bullet during firing would not damage the barrel.
I meant a 90° angled gun. You pull at one end, but all firing happens at the other, out of a straight barrel. Idea being that you can then collapse it to a flat rifle.
I'm amazed that worked for even one shot. Presumably gp was referring to cornershot or something similar, which seems like a much more reasonable approach.