Don't have a milling machine at home, so ..
First machine a tapered mandral on the face plate

Checking for a perfect fit. Lots of 600 grade try and try again.

Sucess, now a little jig to hold it in position

.

Won't bore you with the very painstaking clean up but here she is finished. Now just a wait for the US state department to clear myweapon of material destruction barrels for export.

And bless you Dan Lilja for doing this so promptly.

Regards