drill bit size for 8-40 screw through rail

[gslinger]

What size drill bit would i use to enlarge hole on rail to mount it to reciever.
The hole in rail is for a #6 screw.The action is 8-40 screws.
The 8-40 screws will not fit through rail.
would like to do it myself.
i have a drill press.

THANKS

 

[Edd]

According to the chart, you would use a #18. If the spacing is perfect, you might could use a #19. If the spacing is poor, you might have to use an 11/64ths.