M5 screw depth going into vslot

I'm trying to calculate what range of M5 screw lengths I could use connecting into T-nuts in the vslot grooves. Surprisingly, I don't see a dimension in the vslot cross-sectional drawing from the outer edge of vslot to the central core wall. Does anyone happen to know what that value is? Didn't see it readily on search of forum threads.

Thanks, Scott