They should be the standard m3x6 screws. I would however suggest you switch to titanium or aluminum screws as the nylons as have seen are super weak.
Yes they are meant to shear in a hard hit but the gremlins are so light its a non issue.
I have dropped mine at least 75 feet and it bounced on the grass with just a bent prop. I have flown it near full throttle into a steel pole exploding the camera case and bending the mount and have yet to even scratch the carbon fiber frame.