5/16-18 x 1 1/4 is a brass tip alloy steel socket set screw built for set-screw fastening where a soft contact face is preferred over a hardened point.
Typical uses include instrument fixtures, small control components, and bench-built positioning hardware. The 3A thread fit keeps the screw in the precision set-screw class while the tip changes the way the end contacts the part. Brass gives a firmer metallic contact face when that contact style is preferred over nylon.
Tip installation is handled by Cold Headers in Chicago, giving this category a practical home for soft-face set screw requirements. A nylon insert acts on the thread; a nylon or brass tip acts on the mating surface, so the two product families should not be substituted blindly.
Call 773-775-7900 or email Sales@coldheaders.com for pricing, availability, or a quote.