I did take the barrel off and tighten up the headspace. Does that count?
If you're loading your own (which you certainly will be with a 6x45, so presumably you do for the Blackout as well) - there's no need to "tighten up the headspace" by setting the barrel back. Just adjust your sizing dies to match the chamber, measuring for .001-.002" shoulder bump. When you do that, headspace is perfect regardless how the chamber is cut.
