Perry,
Yes, it is desirable not to have the gas-check or any part of the bullet protrude into the powder area, best to keep it in the neck. The 35 Whelen does have quite a long neck, compared to newer cartridges, and the 3589 bullet was designed around the Whelen. I don't crimp my cast bullets anyway, so the crimp groove for me, acts more as a scraper groove than anything else.

On the Mountain Moulds site, which is what I'm thinking you are refering to, lists the bullet length, this is without the gas-check. the added few thousands won't make too much of a difference. I find the "length inside the case" measurement more useful. Also, his twist rate he lists is a guide, don't take it as gosphel.

Regards,
David.