Mutual Screw & Supply

5/16-18 X 8" Carriage Bolts | A307 Grade A Zinc Plated Steel (50 / Pkg.)

5/16-18 X 8" Carriage Bolts | A307 Grade A Zinc Plated Steel (50 / Pkg.) - Main image
$16.09 $26.82 In stock

5/16-18 X 8" Carriage Bolts in A307 Grade A Zinc Plated 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 Zinc Plated Steel construction
  • Coarse thread for use in wood and with nuts and washers
  • Sold in bulk packs

Specifications

  • Thread Size: 5/16-18
  • Length: 8"
  • Threads Per Inch: 18
  • Material: A307 Grade A Zinc Plated Steel
  • Finish: Zinc Plated
  • Pack Quantity: 25
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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 (5.0 / 5 · 5 reviews)

Christopher ★★★★★

The square neck grabbed into the wood instantly—no spinning or wrenches needed to hold it steady while I tightened the nut. Zinc plating looks clean and even across all fifty, and they’ve held up fine in the damp garage so far.

Victoria ★★★★★

I’ve used a lot of carriage bolts over the years and these are the first ones where the zinc plating actually stayed intact after being torqued down with a socket. The smooth rounded head sits flush enough that I didn’t have to grind anything down on my fence repair.

Harper I. ★★★★★

The square neck on these grabbed the wood instantly and held tight while I cranked the nut down, no spinning or swearing. The zinc coating looks clean and even across all 50 bolts.