How to size used drills

I have all these bits with scored ends, so they have no sizes legible. They are P&N. and Suttons some have a bit of rust others are like new. Some have the ends reduced and like new.

So how do I identify the imperial & metric from number drills? I have only found 1 letter F.


Also some of the metrics are in odd sizes like 6.3, 4.1, so I'm guessing there is a part set in 0.1 increments rather than the usual 0.5

I tried using a vernier but even marked drills seems to be nominal size. The two drill stands I have, Tudor & AF, have different size hold and I have a frost 9/32 that is too fat to fit in either.


At this stage I think I keep the marked ones for accurate work and use UN marked ones for near enough or further boring out.

Open to other ideas? Are the old metal drill guage going to help or again are they nominal.