Self-tapping screw with flute and type B (blunt) tip

[cmac2012]

I've run across this type of screw now and then, a machine screw, usually short - 1/2 inch or less - and stout, that is diameter maybe 1/3 to 1/2 its length. The one pictured here is much longer than that but it's a good photo of the item and there aren't many to be had right off.

I need several - 5/16" long, maybe 1/8 to 3/16 dia. Metric would be about 8mm long by 3 to 5mm.

Anyone seen these on a retail shelf anywhere?