im getting a polish ak kit in trade soon and want to build it on an OOW receiver. from the diagram here it shows the size for the hole as .630 if im reading this correctly. is that correct? since a 16mm drill bit is .6299, couldnt i just get a 16mm drill bit with a 1/2 shank to make the hole? then use something like a 3mm bit to make the small cutouts top and bottom?

noone else has mentioned this in all my googling and searching here on ar15 and i was just wondering if there is something im overlooking?

rivet in your rear block befor you cut any holes in the side

drill out center in steps upto 1/2 in (any bits bigger cost alot)
then just finish opening the hole with a dremel

the drum sander is almost perfect size