Just got a set of Sile J frame banana grips. I can't get the grip screw to thread. If I screw it from the outside of the grip it goes fine. Try it the "right" way and nothing.  I've even tried  screwing into just one panel.

Could the nut be backwards??  If so, is it removable so I can flip it around?

Could I run a tap through it?  Any idea what size?

Thank you

Do you have any pictures? The escutcheon is not meant to be removed, but it can be done. It's very possible that someone mixed up the screws and you have the wrong type, I don't know the TPI for Siles, but I know S&W did change the screw TPI, and length, several times over the years. Although it is odd that it screws in from one side but not the other.

If you choose to remove the escutcheon, make sure to epoxy it in. Be warned, you may irreversible damage the stocks when removing it.

Fixed.  Nut appears to be slightly canted and a small sliver of wood was blocking the hole.  Reamed the inside of the panel with a drill bit and it went right together.