I just did a quick comparison on a grade 5 carriage bolt 1/2-13 and 2" long.

bolt depot
http://www.boltdepot.com/Product-Details.aspx?product=4318


McMaster
http://www.mcmaster.com/#90185A720

Half price from McMaster.

Grigg


1951 GMC 250 in the Project Journals
1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-