Not an expert, but:

The 4/a and 4/b look very like the M&G Diana LG15/16.

The 4/c is I think an M&G Diana LG23.

The 50/II and the 404s look BSF-like to me, especially those grooves at the front of the cylinder and the shape of the rear sight. Although the stock in the drawing looks more like an HW one.