Another thing you need to look at is your head spacing. On some of my stuff, 7x30 waters for example, I have to make a false shoulder. Since 7x30 made from 30-30, I just adjust my sizing die so it does not size all the way down the neck. It leaves a false shoulder to hold the brass in place while firing the fire form round. With a Whelen, worse case scenario, you may have to actually go up to .375 and then back down to 358 if the gun is not head spaced properly.
When you start sizing the brass and opening the neck, don't size the first couple all the way. Try them in your gun to see how they fit. As they open up, that shoulder will sometimes actually increase the length of your brass enough to give you a good reference for head space. (A stock -06 brass should go right in the chamber.) As you start to open up the neck, you should find an area where the brass becomes a little hard to chamber in your gun and it takes effort to close the bolt. Adjust your die to this point. You want that effort to close the bolt as it positions your brass to proper head space. (Don't be fooled if your brass is beyond trim length. You will need to watch that also.) Over length brass can cause the bolt to close hard also. You don't want the case opening to cause the effort, you want the shoulder to cause the effort.
Takes lots of words when typing it out, but just a minute or two when adjusting your die to give you better home made brass when not using the factory made stuff.
Good luck, stay safe, have fun.
Steve