I have an article in an old American Rifleman. There were several hunters that used 35 Whelens for squirrel/rabbit rifles using lightly loaded pistol bullets. After several reloads their cases developed excessive headspace no matter what they did. They finally cured the problem be rechambering to 35 Whelen Improved. The claim was that the small, sloping standard shoulder would not withstand repeated blows of the firing pin without setting back.
Bruce
