bolts

[Steven Clayton <smclayto@npl.uiuc.edu>]

Dear Peter,

I looked up some strength specs for bolts, and it would
seem the bolt we want has at least 3 marks on its head
(5 marks would be even higher strength).  6 of the bolts
Jon gave me have 3 marks; the remainder are blank.
Lowes has some stainless steel bolts of the correct size,
but they are either marked with just a manufacturer code
(and no spec marks) or are marked with a different strength
standard than the one I looked up.  The bolts specified
in the drawing are of A325 steel, which seem to be in
the category of "High Strength Structural Bolts" according
to the table at
http://www.americanfastener.com/technical/grade_markings_steel.asp
I don't know what the specs are of the 10 unmarked bolts,
since 2 of the rows in the table show that unmarked
caps can be A325 steel.  I'm hesitant to buy the ones at
Lowes because I have a feeling they are unlikely to be
better than the ones I have.
Do we go ahead with 16 bolts of uncertain specification,
or should we order some and express ship?
http://www.mcmaster.com/, part number 91571A260
(4", they would have to be cut to 3.5")

Steven