I fire-formed Lapua and some new '69 Lake City match brass, but the downside is a shorter neck. HARD to kill the primer pockets with either of these two types of brass. I used 14g of Bullseye and cream of wheat to fire form with. Accuracy was stellar with both brands of brass at warp speed pushing high pressure.
Forming the brass is a good Wintertime project. I got a 40-gallon trash can, cut a 3/4" hole in the bottom, wound up a roll of Finger Foam and placed that in the trash can. Finger foam is the type that is used in beds to keep old folks from getting bed sores. I fire-formed the brass right in my garage, turning the trash can upside down, and placing the muzzle about 6" down in the finger foam. This produced a very quiet fire forming.
The Lapua brass is particularly tough in the case head, and the Lake City is no slouch either.
All of this fire forming is a tad bit of work, but a guy that likes to tinker needs to stay busy.
To keep doughnuts from forming, I neck turned at 30 caliber, then necked down, never had a problem with doughnuts as part of the thinned neck became part of the shoulder. Neck turning would not be a bad practice for a guy that is necking down 280 AI brass either.
Since I never shot full-length necks, the carbon issue in the necks was never an issue, but a few twists with a brush .015 larger than the neck kept the carbon to a non-existent issue.
I shot that barrel out on Coyotes, rock chucks, and long range jack rabbits. I never wore the brass out. 100 '06 lapua cases and 100 New Lake city brass lasted the entire barrel.