I have a proton that is leaking through grip frame. Through what i believe to be the purge hole. Oring between the asa and grip frame seem to be in good shape. Not sure how much knowledge on the proton there is out there as of now. Just thought I would give it a shot. Hope someone can help Thanks.!
Tighten the two screws on the lower end of the grip frame. Mine did the same thing out of the box. Just tighten those two screws and it'll stop leaking.