I have always fire formed for my 280AI using bullets jammed into the lands to avoid head space problems. I want to try fireforming using a light charge of pistol powder and a filler - no bullet. I am told that I have to form a false shoulder by necking up the 280 necks and them necking them down to 7 mm. to keep the case against the bolt face. Is this necessary? I read Dr. Howell's fire farming article in VH Mag. and he mentions possible head space problems when fireforming cases that do not have rims or belts, but he is not too clear on how to handle this problem.

Ok, I've done this when making .40jeffery cases from .375RUM case. I size the RUM case w/o the expander until the bolt just crush fits when closing. Then I load w/ 27gr+/- of a slow pistol powder like 4227 or 2400. A small amount of Dacron on top of that & fill w/ COW then cap w/ a melted wax plug. Fire in safe direction, instant .404j case. I don't see why this wouldn't work for any round. You may have to exp. w/ a powder charge though.
Personnaly, if making rounds for an ai, I just use 3-5 loaded rounds every time I go shoot, just to clear the bore & make sure my chrono is working. After awhile I have 40rds of OFB.

If your 280 Ackley was properly chambered A virgin 280 Rem case should be a crush fit, No need to seat bullets long or put om a false shoulder. The proper Ackley chamber is shorter than the standard chamber,
Lyle

I have an Ackley chamber that was made with a standard headspace gauge

I have tried 100 things, and settled on lubing the brass and chamebr with Lyman moly bore creame, 10 or 15 gr of pistol powder, and cream of wheat to the top. If I can't shoot straight up [like at a range with a range master] with gravity keeping the c.o.w. in place, I put some Ivory soap on the case mouth.

That gets the Ackley shoulder mostly formed, but not perfect. The next load is a standard Ackley load with bullet with as good accuracy as ever, and after that load, the shoulder will be perfect.