Chamfer instead.

I load alot of 300 Win Mag. 200 gr. Sie Match, never bell case mouth, just uniform the necks, actually just clean up the necks not a complete turning. Its my LR Varmint rifle. Slight bevel to inside case mouth.
I built it off a Savage BP'd action, Lilja HV bbl. 28" Choate Ultra Varmint stock,Basix trigger set to 8 oz.Niteforce 5.5x22. Areal tack driver. Keeps 3 shots into 1/2" at 500 yds. Five shot groups hover 7/8 to an inch at the same distance but that is me, the rifle will do better, the blasting with my 475 Linebaugh doesn't do much for my LR precision shooting. But back to your question, you don't have to bell the case mouth.

Been loading the 30-06 since 1959 and have put together many thousands. Like Lee, I have never belled a case mouth for jacketed bullets. Just a bevel on the inside of the case mouth will do. I use an old Vickerman straight line bullet seater.

Dupont and later IMR 4350 is my go to powder unless the rounds are going in a Garand and then it is 4895.

raise the ram after putting the bullet on top of the case until you feel it enter a small amount. Then lower the ram and twist the case (with the bullet partially seated) about 1/2 turn and finish seating.

For the life of me I feel that if it starts a little cock-eyed, then the twist and final seating will even things out somewhat. May not be anything to it , but it makes me warm all over that my bullets are seated somewhat concentrically.

Bob