They are suggesting the screws are #8? They look more like 1/4" to me.
They're neither. Took one of mine to a bolt & screw company and they
couldn't match them up with anything they had. The #8 was close, but the
threads weren't as tight as the forearm screws. Need to go to a well
supplied gunsmith, I would say.
When I had a similar problem, I just drilled the forearm holes a sixteenth
inch deeper. It's tricky, cuz the drill bit wants to dig in, but it can be done.