First of all, the .35 Brown-Whelen is not a standard cartridge, so no one can say your .35 B-W is the same as his .35 B-W. .35 B-W reamers made by different makers can vary, resulting in each rifle being truly a law unto itself.
To understand the .35 B-W, we have to understand the Ackley Improved (AI) cartridges. The AI cartridges are standard rounds with a sharpened shoulder. The AI chamber leaves the shoulder in the same place, simply changing the angle. AIs were touted as more powerful, but now that chronographs and pressure measuring equipment is available, the AI at the same pressure as standard cartridges don't show enough velocity increase to be meaningful.
The Brown-Whelen chamber is different -- it not only sharpens the shoulder, but also moves it forward. This means the shoulder has no support at all, and firing a standard cartridge in a Brown-Whelen chamber can split the shoulders (about 100% of the time in my rifle.)
For that reason I use a special forming charge in my .35 B-W, consisting of several grains of Bullseye held in place by a square of toilet paper (and no bullet.) Bigfoot Wallace, my .35 B-W is an '03 Springfield customized by C. W. Fitch of Phoenix in the late '60s or early '70s. The Mauser-style extractor holds the case against the bolt face, and the results are close to perfect. Cases cannot be formed in this way with push-feed rifles, because the case will simply slide ahead of the bolt.
If your .35 B-W will form factory .35 Whelen cases with no splits, go ahead and form them that way -- but be sure you wear protective glasses, because you never know.