Verified answer

it's in autocad ,help folder then tutorial folder :)

for the ones that come bundled with autocad look in your main autocad directory, sample sub dir, then the designcenter folder. you should see the dwg that your bolt is in there.

or you could try the dc online tab in the design center, find what you want and drag to your dwg.

good luck

Draw it yourself for god's sakes and then save it into your own library. In the time it took you to post this question you should be able to already have it drawn.