Chounin A wa Akuyaku Reijou o Doushitemo Sukuitai: Dobu to Sora to Koori no Himegimi - Vol. 2 Ch. 10 - The Goblin Labyrinth

[Flyingpantsu]

So first he was an aeronautics engineer then now he can make assault rifles. Bruh.
If you're good enough to make guns through alchemy, don't limit yourself to standard designs and make a fully custom gun.
I bet the author had a AK47 airsoft replica lying around and couldn't be bothered to draw something else.

 

[Monovar]

I like how the cow's tail kept hitting the old man. Details like that really set this manga apart.