Hobbies And Interests
Machine Screws
Scope mounting screws are a different class of fastener than typical screws. They are really a kind of bolt called a machine screw. Machine screw is another name for a bolt used in a precision applications. Machine screws are generally threaded all along their shaft, unlike a through-bolt with a smooth shaft and threads on the end. The full-threading makes a positive mechanical connection in two or more discrete threaded components, rather than just holding two components together with tension.
Set Screws
A set screw is another kind of machine screw that doesn't have a head to mechanically bind the screw in place. Set screws, sometimes called locator screws, can be used for fine placement of mechanical objects. They tend to be small because their role is seldom to provide the strength of a mechanical connection, but rather establish the specific location of a connection before it is fastened with heavier machine screws.
Threads
Compared to a typical bolt, mounting screws have more and smaller threads. They are said to be finely threaded. Mounting screws also have less lead. The lead is a function of the angle at which the threads are cut. It is the vertical distance the screw travels per revolution of the screw. Fine machine screws tend to have a low lead, and screws used for adjusting have an even lower lead, so, for example, a single turn will make a very fine adjustment.
Coatings and Materials
Rifle screws may be made from a special steel alloy, but all rifle screws must be protected from corrosion -- primarily rust. One way to protect against rust is to use alloys that are high in chromium or nickel. Another way is to use stainless steel fasteners. The most common way, because other rifle components are still exposed to corrosion, is to treat them with a gun-bluing agent, turning the dark gun-metal blue. This gives them a degree of protection from moisture.