On Mon, 12 Dec 2016 16:35:44 -0800 (PST), DerbyDad03 advised:

Is there a Fastenal near you? Grainger?

Thanks for that link to Fastenal.
It looks like they also don't have the 2-3/4-inch 3/8ths inch bolt.
They just have the 2-1/2 and 3 inch just like Home Depot did, only the
Fastenol bolts are stainless steel.

Pricey though, at almost nine dollars each which is almost as much as the
entire bead breaker cost just for the four bolts to bolt it down.

3/8"-16 x 2-1/2" ASTM A193 Grade B8 Stainless Steel Heavy Hex Cap Screw
Fastenol SKU: 0175831 (Wholesale price $8.64 each).

Interesting difference in price though:

3/8"-16 x 3" ASTM A193 Grade B8 Stainless Steel Heavy Hex Cap Screw
Fastenol SKU: 0175833 Online price $1.20 each