As usual, both of the stories from Blackhawk 131 (Dec. 58) that I will be talking about are by Dillin and Cuidera.
The first story in the issue sees the return of the Jailer.
Although the Blackhawks remain suspicious of him, the Jailer insists that he has now gone straight. He still wears his costume, and devises traps, but uses these to catch fleeing criminals, and turn them in for reward money.
But Blackhawk's suspicions are not allayed. He continues to follow the Jailer, and discovers that the man is also stealing the hidden loot from the criminals that he captures. Blackhawk turns the tables on the Jailer, and sends him back to prison.
The Jailer does not return until 1964.
The second story brings to mind the Rainbow Batman, although the stories have nothing in common.
The story pits the Blackhawks against a villain, Mr. Beam, who has a "colorama" gun, which affects everything of a certain colour. When Mr. Beam attacks the team at a museum, it hits their blue costumes, as well as statues made of them (which are said in the text to be blue, although they are white), but does not affect Chop Chop, because his costume is not blue. Blackhawk dresses everyone up in green for the next encounter with Mr Beam, but he alters his gun, and sends them flying into the air.
So Blackhawk gives everyone a different coloured costume, so that at least one of them will be able to face Mr. Beam, no matter what his gun is set to. This doesn't work out either, as the colorama gun is able to adjust too quickly.
So Blackhawk covers his costume in oil, rendering it jet black. The colorama gun only affects the colours of the rainbow, so Blackhawk is able to defeat him.
It is also worth noting that Blackhawk's original costume, back in the early 1940s, was the jet black colour of his suit on the last page.