heatbed holes

I am wondering is it possible to make the holes larger on a heatbed so i can use m4 bolts as my i3 y plate holes are tapped out to m4. I was going for a standoff with a spring to fit over it(for bed leveling purposes) but don't want to get custom made standoffs m4 male to m3 female, it be easier if i can make the holes bigger?

They are very close to edge so I think there is a fair chance they would break out while being drilled.

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[www.hydraraptor.blogspot.com]

yes i seen looks like i will get someone at work to make me a set of custom stand offs