Possible Clues:

• "Well, I'll be darned!"
• Rogue (with a shooter for a father?)
• 'Darn it all!'
• Jocular form of address (for Colt's relative?)
• Jocular issue of Browning, perhaps?
• Rogue has issue to do with weapon
• Rogue whose dad keeps getting fired?
• Rascal
• Jocular or affectionate term for someone (whose parentage might be in doubt?)
• Said with some affection about him that the canon has a baby