Metallics JCB27 Bolts 3/8-16 x 3-1/2 Carriage Blt St (Jar 25)

Rated 60,000 psi minimum tensile and 36,000 psi minimum yield, with a hardness of Rockwell B70 to B100. That is low-carbon steel strength, equivalent to an unmarked Grade 2 class fastener, which is appropriate for general framing, blocking, and equipment mounting. For structural steel connections or anywhere a drawing calls out a higher grade, this is not the bolt.

Steel with a zinc finish, which handles damp and occasional weather exposure but is not stainless or hot-dip galvanized. For deck framing in pressure treated lumber, coastal exposure, or permanently wet locations, specify a hot-dip galvanized or stainless carriage bolt instead. Interior, dry, and protected exterior work is where zinc plating belongs.

No. The JCB27 is not Buy American compliant and not ARRA compliant, with country of origin listed as multiple. On federally funded or domestic-content work, source a domestically produced carriage bolt instead.

Each jar holds 25 bolts, and 25 each is also the order minimum, so a jar is the smallest buy. Metallics notes other sizes and quantities can be had by request.

The JCB27 is built to ASME B18.5-1990, the round head square neck bolt standard. Any other 3/8-16 x 3-1/2 bolt made to that same standard will have the same head diameter and square neck geometry, so it drops into existing holes and matches what is already installed on a repair or add-on.

A carriage bolt like the JCB27 is for a through-bolted joint where you want a low, smooth mushroom head on the show side and nothing to snag or grab with a wrench. The square neck locks it in wood so you tighten from the nut side only. Use a hex bolt instead when you need to hold or torque the head, and a lag screw when you can only reach one side of the connection and cannot run a nut on the back.