Countersink screw info needed

[qatmix]

Hi Guys

I'm currently working on a CAD shock tower. I want to have some holes countersunk.

The screws are 3mm, can anyone tell me what angle the heads are for common metric countersunk holes? is it 45 degrees?

Also, as this will be machined in 3mm carbon fibre, should I make the screw holes 3mm or 3.1mm to ensure that it's not too tight.

Thanks
C