Metallics JSHC3858 3/8-16 x 5/8 in. Socket Head Hex Cap Screws - Alloy Steel Black - Each

The JSHC3858 is internally wrenched with a hex (Allen) drive, and the socket depth is 0.182 in. On a 3/8-16 socket head cap screw built to ASME B18.3, that is a 5/16 in. hex key. Head width measures 0.55 to 0.562 in. and head height 0.368 to 0.375 in., so a standard 5/16 key seats fully without a deep counterbore.

Yes on tensile. The JSHC3858 alloy steel socket head cap screw is rated 180,000 psi minimum tensile and 162,000 psi minimum yield, where a Grade 8 hex head cap screw of this size runs 150,000 psi tensile. Hardness is Rockwell C39. Because it is wrenched internally rather than across the flats, it also gets that strength into a smaller footprint, so you need less bearing surface or counterbore diameter than an external-wrench hex head.

Yes. The thread is 3/8-16 UN, 16 threads per inch, which is standard 3/8 in. coarse. It mates with any 3/8-16 tapped hole, 3/8-16 strut channel nut, or 3/8-16 hex nut. It will not fit a 3/8-24 fine-thread hole.

No. The JSHC3858 is not Buy American compliant and is not ARRA compliant; country of origin is listed as multiple. If your contract carries a domestic-sourcing clause, this part will not satisfy it.

The JSHC3858 is plain alloy steel with a black finish, which is an oil/oxide type surface, not a plated corrosion barrier. Keep it to dry interior work: electrical, plumbing, heating and air conditioning applications indoors, inside enclosures, or anywhere it will be painted over. For wet, exterior, or washdown locations use a zinc-plated or stainless fastener instead.

They ship in a jar, 100 pieces minimum per jar, under part number JSHC3858. So a single order line gets you 100 screws, not one. Useful to know if you only need a handful for a panel job, and useful if you are standardizing 3/8-16 hardware on a cart or service truck.

Dimensions follow ASME B18.3-2012, the standard for socket head cap screws, so head geometry matches any counterbore detailed to that spec. Confirm against the measured head: 0.55 to 0.562 in. across and 0.368 to 0.375 in. tall.

Alloy steel at Rockwell C39 with 162,000 psi minimum yield gives real preload capability rather than brittle failure at the socket. Elongation is 10 percent minimum and reduction of area 33 percent minimum on machined specimens, so there is measured ductility behind the hardness. Use a proper 5/16 hex key or bit socket and keep it fully seated; a worn key is what rounds out a socket head, not the material.