Metallics JBSC51634 5/16-18 x 3/4 in. Socket Button Head Hex Cap Screws - Alloy Steel Black - Each

Plan for a head about 0.527 to 0.547 inch across and 0.152 to 0.166 inch tall on the 5/16-18 JBSC51634. That low profile is the reason to pick button head over a standard socket cap screw: it sits close to the surface where a taller head would foul a panel, a slide, or a cover plate. If you are counterboring, size the bore to the upper end of the head width range.

If the hole is 5/16-18 UNC, yes. The screw is a 5/16 diameter at 18 threads per inch, Unified (UN) thread form to ANSI/ASME B1.1, which is the standard coarse pitch for 5/16 hardware. It will not engage a 5/16-24 fine-thread hole, so confirm the pitch before you order.

Rated at 7300 lb minimum tensile with a core hardness of Rockwell C39-44. That is plenty for strut, enclosure, bracket and equipment mounting work, but the manufacturer states these screws are not recommended for critical, high-strength applications. For anything load-bearing or life-safety, specify a fastener with a published grade for that use.

No. These Metallics cap screws are not Buy American compliant and not ARRA compliant, with country of origin listed as multiple. On a job with Buy America or ARRA domestic-content language, you will need a fastener with a documented domestic origin instead.

It takes a hex (Allen) key, not a screwdriver. The socket button head on the JBSC51634 is hex drive, with a socket depth of 0.105 inch, so your key needs to seat fully to avoid stripping the recess. Keep a ball-end key out of it for final torque; use a full-engagement key in the socket.

Treat the black as appearance only. The screws are alloy steel black and are supplied plain, with no plating or protective coating called out. Bare alloy steel will rust in wet or exterior service, so keep these to dry indoor and enclosed applications and go to a plated or stainless screw for outdoor, damp, or washdown locations.

They ship in a jar of 100. The order minimum is one jar, so 100 pieces is the smallest quantity, and that jar weighs 1.72 lbs. Other sizes and quantities can be arranged by request.

Yes. Head and socket dimensions follow ASME B18.3-2012, the standard for socket cap screws and hex keys, and the threads follow ANSI/ASME B1.1. That matters if a submittal or spec sheet calls out a B18.3 socket screw, because the head will interchange dimensionally with any other screw built to that standard in the same size.

Pick the button head when clearance or appearance governs. Its head stands only 0.152 to 0.166 inch tall and spreads load over a wider 0.527 to 0.547 inch bearing face, which suits sheet metal and cover plates. A standard socket head cap screw has a deeper socket and a taller head, giving more drive engagement and higher strength for tightly torqued or load-carrying joints. Since these black alloy screws are explicitly not recommended for critical, high-strength applications, move to a graded socket head or hex bolt for those joints.

Metallics builds the BSC series for electrical, plumbing, and heating and air conditioning work, which is where a 3/4 inch long 5/16-18 screw lands: mounting enclosures and boxes, fastening brackets and equipment feet, strut and channel accessories, and panel covers where a low head profile keeps the screw from catching. With only 3/4 inch of length, your combined grip plus thread engagement has to stay under that.