Metallics JBLS44SS Bolts 5/16 X 4-1/2 Hx Lag Blt SS (Jar 50)

The Metallics JBLS44SS lag bolt is made from 18-8 stainless steel, which gives it better corrosion resistance than a galvanized steel lag. That is what makes it the choice for exterior mounting, coastal exposure, wet locations, and treated lumber where galvanized coatings get chewed up.

Measured shank diameter on the JBLS44SS runs 0.298 to 0.324 inch, so you are drilling for a nominal 5/16 shank. In softwood a pilot close to the root of the thread is enough; in hardwood or dense material drill nearer the full 0.298 inch shank size so the stainless shank does not gall or snap while driving. Threads are 9 per inch, so it bites coarse and fast.

It has a gimlet point, so it will start in wood without a punch, but it is a lag screw and not a self-drilling fastener. Predrill a pilot in anything structural or dense. The hex head takes a wrench or socket, not a screwdriver, and head across-flats measures 0.484 to 0.500 inch, so a 1/2 inch socket is the driver.

Tensile strength on these stainless lags is approximately 100,000 to 125,000 psi minimum, with hardness in the Rockwell B95 to C32 range. That is ample for hanging conduit racks, strut, equipment brackets, and fixture backing into wood framing. For a spec drawing that calls out a specific bolt grade, match the drawing; the strength figures here are the values the manufacturer publishes.

It is flagged as both Buy American compliant and ARRA compliant, with country of origin listed as China. Institutional and government buyers working to a funding clause should read both of those together and confirm which clause their contract actually invokes.

Dimensions follow ASME B18.2.1-1996, the standard for square and hex bolts and screws. A hex head at 0.484 to 0.500 inch across flats and a 5/16 nominal shank means it drops into the same holes and takes the same 1/2 inch socket as any other standards-built 5/16 hex lag on the site, so you are not changing tools mid-run.

Go stainless. 18-8 stainless resists corrosion better than galvanized steel, and the copper-based preservatives in modern pressure-treated lumber are hard on zinc coatings. Where the fastener is buried in treated wood or exposed to weather, the stainless JBLS44SS is the one that stays serviceable; galvanized is the cheaper pick only for dry interior work.

The jar is bolts only, 50 of them. Plan on ordering flat washers separately if you are pulling the head against sheet metal, strut, or soft wood, and use stainless washers so you are not mixing metals against an 18-8 stainless bolt.

Other sizes and quantities in the BLS and JBLS stainless lag range are available by request. The JBLS44SS covers 5/16 x 4-1/2 in a 50 count jar; if you are standardizing a building on one diameter across several lengths, ask for the sizes you need from the same series.