5/16? don't think so....

[Mark Pruitt]

Quick trip to the BORG.....maybe a bit TOO quick.:o I snatched up a bag of 5/16" washers, brought 'em home, opened the bag and surprise--they're 3/8" in a 5/16" bag. Good thing I was just stocking up and not in desparate need...otherwise this might not be funny. But I can't stop laughing. In the picture, to the left is a 3/8" drill bit, to the right is a 5/16" bit. Hilarious! Thought I'd share.:p Guess I'll look more closely next time I snatch a bag of washers off the hanger.

[Frank Chaffee]

Mark,
Here are some specs for 5/16” USS flatwashers… http://www.fastenal.com/web/products/detail.ex?sku=33006
Note that the ID is indeed .375”. SAE washers will have smaller ID and OD.
Frank

[Mark Pruitt]

Frank,
All I know is, the boxes of 5/16" washers I've been buying in the past (and yes they said 5/16") were considerably smaller than this.

[Matt Meiser]

I've found that to be true as well. I've found that using one size too small usually snugly fit the shank of the bolt, and according to the spec Frank posted, that's not a coincidence.