Several rare sketches by Franquin from 1950, studies which he created for his short western story 'Spirou and the Black Hats' ('Les Chapeaux Noirs'). The story he created after his stay in the US with Morris and Jijé, in which Spirou and Fantasio visit the Wild West. It was serialised in Spirou magazine 617-635 and published in comic book form in 1952, together with two earlier short stories by Jijé and another by Franquin ('Mystère à la frontière', published in Spirou 636-652).
For comparison, I've put some images from the story below (Dutch version). I think at least two of the sketches above were created for the bottom half of page four:
In the story, Spirou and Fantasio are journalists for the magazine 'Le Moustique' (for which Franquin and Morris also worked as cartoonists). They visit Tombstone to write a story about the 'Old West' and get into a gunfight with some severe outlaws, at least that's how it seems at first. Only later they discover the town is actually used as a movie set. The sketches of Spirou from the back, shooting at the outlaws seem to have been made for the bottom half of page eight: