On Friday, 26 January 2018 15:30:17 UTC, Dave Plowman (News) wrote:
Why is it so difficult to buy 4mm 'bolts' with hex heads?

Everyone sells Pozi, both countersunk and raised and slotted types too.
And plenty with allen heads.

But for this partially obstructed application, I can only get to the sides
of the head.

Obtainable from Model Engineering supplier.