Mutual Screw & Supply

5/16-18 X 3-1/4" Carriage Bolts | Fully Threaded | A307 Grade A Plain Steel (600 / Pkg.)

5/16-18 X 3-1/4" Carriage Bolts | Fully Threaded | A307 Grade A Plain Steel - Main image
$88.58 $119.7 In stock

5/16-18 X 3-1/4" Carriage Bolts in A307 Grade A Plain Steel. Carriage bolts feature a smooth, rounded head with a square neck underneath that pulls into the material to prevent the bolt from turning during installation, making them ideal for wood-to-wood and wood-to-metal connections.

  • Domed head with square anti-rotation neck
  • A307 Grade A Plain Steel construction
  • Coarse thread for use in wood and with nuts and washers
  • Fully Threaded
  • Sold in bulk packs

Specifications

  • Thread Size: 5/16-18
  • Length: 3-1/4"
  • Threads Per Inch: 18
  • Material: A307 Grade A Plain Steel
  • Finish: Plain
  • Thread Style: Fully Threaded
  • Pack Quantity: 600
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Standard Shipping · United States: $0.00

Express Shipping · United States: $3.99

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United States · Return window (days after delivery): 30. Return method: By mail. Return postage: Seller pays.

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Customer Reviews (5.0 / 5 · 5 reviews)

Natalie ★★★★★

I needed a bulk set for a deck repair, and these 600 bolts in Grade A steel are exactly the right spec for outdoor framing. The fully threaded shafts make it easy to cut down if needed, and the dome head gives a clean look.

James ★★★★★

The square neck on these carriage bolts grabbed the wood perfectly, no spinning while I tightened them down. Good solid feel to the steel, and having 600 in the box means I'm set for multiple projects.

Matthew P. ★★★★★

Installed a whole deck’s worth of these and not a single one spun on me, that square neck under the head bites in just right. The 3-1/4" length is perfect for going through 2x material with room for a nut and washer. At 600 per box, I’ve got plenty left for future projects.