Mutual Screw & Supply

5/16-18 X 3-1/2" Carriage Bolts | Fully Threaded | 316 Stainless Steel (50 / Pkg.)

5/16-18 X 3-1/2" Carriage Bolts | Fully Threaded | 316 Stainless Steel (50 / - Main image
$21.12 $30.17 In stock

5/16-18 X 3-1/2" Carriage Bolts in 316 Stainless 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
  • 316 Stainless 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: 3-1/2"
  • Threads Per Inch: 18
  • Material: 316 Stainless Steel
  • Finish: Plain
  • Thread Style: Fully Threaded
  • Pack Quantity: 50
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Standard Shipping: Handling (business days) 0–1; Transit (business days) 7–15.

Express Shipping: Handling (business days) 0–1; Transit (business days) 7–15.

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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 (4.8 / 5 · 5 reviews)

Ryan ★★★★★

I’ve been using these fully threaded 316 stainless bolts for a dock repair, and the square neck locks in tight without any spinning. The 5/16-18 size was a perfect fit for my pre-drilled holes, and the 3-1/2” length gave me enough thread to secure everything firmly.

Leo ★★★★★

The square neck on these bolts grabbed instantly when I tightened them, no spinning at all. I’ve used cheaper zinc-plated ones before that would strip, but these 316 stainless ones feel rock solid after a few days outside.

Alexander ★★★★★

The 316 stainless steel has held up perfectly on my deck railing through two weeks of rain without a single rust spot. The square neck pulls in tight just like it should.