Yes the Brown has the shoulder pushed forward, there is aslo another wildcat based on an -06 case with the shoulder moved forward and necked to 35 but the name escapes me.
If you get more than 50 fps gain with the ackley or brown it's achieved solely by running high pressures. Been there, done that and had it rechambered to a 350 Rigby.
Honestly I don't think the std whelen has any problem with headspacing. I believe the issue is it's one of the oldest wildcats and hence there were likely variances in chamber reamers as well as the skill of gunsmiths not to mention hand loaders that were setting back shoulders.
Personally I prefer the way the original whelen feeds from the magazine vs. the improved version and could care less about 50 fps.
