I used a cutoff tool bit to do my flange and stub nibbling. I've found I get better control over very small increments than with a "proper" cutting bit. Just one of my many eccentricities.
I've also acquired a wrench and barrel vise from a member on ARFCOM who got them on eBay. They work pretty well, with a couple modifications. My old barrel pulling/installing tools were pretty crude...
I make sure I have a squib rod in the barrel when tightening the barrel vise down (not shown in pics).
Edit: The brass thingy in the chamber is a mandrel for holding the breech so I can turn it concentric with the bore/chamber. It's cut the same taper as a Parabellum cartridge.