I run the Lapua brass and neck it down in 4 or 5 steps to reduce the stress on the brass and have yet to see a doughnut, as opposed to a buddy who does the 6cm in 1 step and is getting doughnuts after about 5 firings in Hornady brass. I tried necking down 6.5 in 2 steps and 6 in 1 step and was never really happy with how it turned out. I have been running this cartridge for 3 yrs and it is by far my favorite round for coyotes, pigs and white tails. In my group, 4 out of 6 of us shoot a 22cm, the 5th guy runs a 22x47L and #6 is a weird cat with a 22 dasher.

Three of the 22cm guys are running the 69tmk with 39.0 of varget at 3595 froma 24" 8tw and 3510 from a 22" 8tw and 3500 from a 20" 8tw. The Dasher guy runs the 88eldm and is racking up some nice kills. I run whidden f/l bushing dies, the 80.5 berger, 42.2gn of H4350 & cci450's from Lapua brass for 3393fps from a 22"8tw with an sd of 6. It knocks the stuffing out of coyotes and isn't horrible on fur, but the insides are soup.
We have found that the Alpha brass showed pressure spikes well before the Lapua brass and just wouldn't give the velocity normally found with added pressure. Lapua has been, hands down, the best brass option we have found. There are guys running the 90+ bullets from 7.5tw and showing excellent results, but mine is a critter gitter and the 80.5 fullbores are bada&& on everything that I have shot with them. The Hornady 88gn ELDM's are killing very well also, from a local state coyote hunter. The 80.5 are easy to tune and have no qualms about a jump. Once you get it up and running, you will grab it more often than not for a good time.