.300 Whisper Case forming.

[CKOD]

Anybody have advice or tips for forming a .223 case into a .300 Whisper case? I'm contemplating building an AR chambered in .300 Whisper.
While it doesnt look too hard to do I'm sure there are a few gotcha's.

Any suggestions for trimming all that brass after I size it? .3 inches is a good bit. Should I worry about annealing the cases for a longer life?

I was considering building an AR in 5.7x28 but the blowback action streching the case neck making it not last long was a turn off.

 

[JJD]

unless you have a sloppy chamber you will have to neck turn

For my cases that have to be cut down a lot I use a pipe cutter or a lathe.

My 30-221 does just fine with Fireball brass