I think that pretty well answers the question, obvious the plate fits tight! In the 'seated' position, I can see about a .002-.003 thousands clearance between the receiver and the breech block plate. As to sticking................whatever works for you!
While we're on the' paper cutters', have you tried the brass powder cases? I bought one to see how they work, the Pedersoli brand, it fits my IAB but goes in about .004, that's using the standard 'Christmas tree' bullet. The brass 'shell' has a recess for a bullet and the Xmas tree bullet slops around.