4-40 x 5/16 316 Stainless Steel Button Head Socket Cap Screw helps engineers combine reduced head projection with 316 stainless steel corrosion resistance in equipment that sees moisture or cleaning cycles. The button-head design gives engineers a compact rounded profile, a broad bearing surface, and internal hex drive access, while the 316 stainless steel material is selected where additional corrosion resistance is needed compared with general-purpose stainless grades.

Typical applications include pump assemblies and valve systems, where the internal hex drive allows controlled installation around compact housings and service covers. It can also serve commercial equipment and outdoor hardware, where 316 stainless steel is useful where humidity, weather, or cleaning exposure may be present. Engineers choose the button head when the screw remains above the surface and a smoother exposed appearance is preferred.

For the 4-40 thread and 5/16 in. length, the reference head diameter is 0.201-0.213 in. and the head height is 0.051-0.059 in. The reference dimensions below help engineering and purchasing teams compare head height, head diameter, and hex-key requirements.

Technical Highlights

• Material: 316 Stainless Steel
• Thread Size: 4-40
• Length: 5/16 in.
• Nominal Body Diameter: #4 (.112 in.)
• Head Diameter: 0.201-0.213 in.
• Head Height: 0.051-0.059 in.
• Hex-Key Size: 1/16 in.
• Drive Type: Internal Hex

Reference dimensions may vary slightly by manufacturer.

Call 773-775-7900 or email Sales@coldheaders.com for pricing, availability, or a quote.