A blue-nosed automatic?

Question

Take this passage from Agatha Christie's The Seven Dials Mystery.

"Do you think you could go out and buy me a pistol, Stevens?" "A pistol, sir?" True to his training, Stevens betrayed no hint of surprise. "What kind of a pistol would you be requiring?" "The kind where you put your finger on the trigger and the thing goes on shooting until you take it off again." "An automatic, sir." "That's it," said Jimmy. "An automatic. And I should like it to be a blue-nosed one—if you and the shopman know what that is. In American stories, the hero always takes his blue-nosed automatic from his hip pocket." 180 Stevens permitted himself a faint, discreet smile. "Most American gentlemen that I have known, sir, carry something very different in their hip pockets," he observed. Jimmy Thesiger laughed.

In this passage, what is a "blue-nosed" gun?

In addition, in the 1930s, what would a fictional american gentleman be keeping in his hip pocket?

Answer 1

Here's a forum discussion on suspect is armed with a blue nose revolver that failed to come to any conclusion. But we here at ELU are made of sterner stuff...

This Wikipedia article on the Colt Detective Special revolver says

The Detective Special was initially available in both bright blued and nickel finishes...

I doubt Agatha Christie expected many of her readers to get that reference. She may simply have used it for artistic effect - "blued steel" implies heat-treating, which can either be taken to mean it's a higher-class weapon that's been more carefully manufactured, or maybe that it has been used (the blueing by implication arising from the heat of firing).

Answer 2

With the very greatest respect to the author, she has confused a self-loading pistol with a fully automatic weapon, more commonly referred to as a machine-pistol. Thesiger has Stevens buy a "blue-nosed automatic", which is later described as a Colt, possibly a 1903 Colt Pocket Hammerless. This pistol had a blued finish, a heat and chemical treatment process which has long been a common method of resisting corrosion and imparting a pleasing appearance. Another "automatic" which appears in the story is a Mauser, possibly the 1914 model, also in a blued finish.

So to answer the original query — there's really no such thing as a "blue-nose gun", as any blued weapon will be treated on all its external surfaces — the whole thing will appear a dark blue.