[Mr Kidnapper]

For an experienced 3D artist it'd probably take two hours to make a gun that looks like what it should be. It'd take longer, perhaps a day or three, to make one that was as detailed as the original. It'd take about less than a week to make one that was both low poly and as detailed as the original. Normal maps help that process a lot. Owning said gun helps a lot. This is based on work from hobby developers, who tend to put in more time and detail into the things they make as compared to professionals.