There is no "headspace memo" with the 400 Whelen. It headspaces fine on the shoulder it has and in 1000+ rounds of load development I never once had a failure to fire or had any of the mythical headspace issues falsely associated with this round. A google search for 400 Whelen will find articles of the late Michael Petrov which soundly dispel any headspace myth common to the 400 Whelen.
