Metallics JBLS16SS Bolts 5/16 X 4 Hx Lag Blt SS (Jar 50)

The JBLS16SS is a 5/16 inch diameter by 4 inch long hex head lag bolt in 18-8 stainless steel, packed 50 to a jar. The jar of 50 is also the order minimum, so you buy it as a full jar rather than by the piece.

Measured shank outside diameter on the JBLS16SS runs 0.298 to 0.324 inch, with 9 threads per inch. Stainless lags gall easily, so drill a pilot sized to the root rather than the full shank and treat the hole as required, not optional, in hardwood or dense framing.

Yes. The JBLS16SS is 18-8 stainless, which Metallics rates as having superior corrosion resistance to galvanized steel bolts. That makes it the pick for exterior mounting, coastal or damp mechanical rooms, and anywhere a galvanized lag has already rusted out once.

Across the flats the hex head measures 0.484 to 0.500 inch, so a 1/2 inch socket or wrench is the driver. There is no slot or drive recess in the head; it is a hex head lag that gets turned with a wrench or impact socket.

Approximate minimum tensile strength is 100,000 to 125,000 psi, with hardness in the Rockwell B95 to C32 range. Stainless does not carry a steel grade marking like a Grade 5 lag, so those figures are what you spec from on a submittal.

The JBLS16SS is manufactured to ASME B18.2.1-1996 for dimensions, so head and thread geometry matches the standard hex lag screw callout on a drawing. It is also flagged ARRA compliant and Buy American compliant.

A lag like the 5/16 x 4 JBLS16SS is for fastening into wood framing or a wood blocking member where you only have access from one side. It has spaced threads and a gimlet point that cut their own thread in the wood. If you can get behind the member, or you are fastening into concrete or steel, a through bolt or an anchor is the correct fastener instead; a lag has no mating nut.

The jar contains the 50 hex lag bolts. If your detail calls for a flat washer under the head to spread bearing on wood or to seat a slotted bracket, order washers separately in 5/16 size.