as long as your getting black oxide for any m3 screw it would be harder to find non class 12.9 tbh.

just to add, replacing screws should be on the list of things to do occasionally. every faster is subject to plastic deformation given enough stress over time. its cheap insurance

just a side note,

https://www.amazon.com/gp/product/B01AHRLNPQ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

get one of these, everyone should have one

As a tangent. M3 SCREW CUTTER

https://www.amazon.com/gp/product/B01AHRLNPQ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

this is for cutting metric screws. its hard to find if your in the USA but you can make any length of screw and cut it down without any trouble.