Tips for Using Hock Plane Blades in Stanley Planes?

I'm having some trouble getting my Hock blades and chip breakers to work properly in my old Stanley No. 4 and No. 5 planes. The blades feel really thick—when I try to advance them to make a cut, it completely closes up the mouth. I thought about filing the mouth a bit, but it seems like I'd have to remove a significant amount of material which feels excessive. The Stanley blades have always worked fine, so I'm wondering if I need to adjust the frog to accommodate the Hock blades instead. Any advice on this would be greatly appreciated!