RE: Weatherby Accumark 30-378 stainless/brake
 

pierrecham:

You can't go wrong with a Weatherby Mark V Accumark. I and myfriends obtain well under 1.00" at 100m three shot group.

I have always compaired cartridges by matching Sectional Density (SD) as close as possible.

The .30-378 Wby. Mag. using a 200 gr. Nosler Partition (SD: .301) at the muzzle has 4434 ft/lb. At 500 yds. 2188 ft/lb.

The .340 Wby. Mag. using a 250 gr. Nosler Partition (SD: .313) at the muzzle has 4801 ft/lb. At 500 yds. 2286 ft/lb.

If both calibers are zeroed at 300 yds., at 100 yds. the .30-378 Wby. Mag.shoots .70" flatter; at 400 yds. the .30-378 Wby. Mag. shoots 1.80" flatter; at 500 yds the .30-378 Wby. Mag.shoots 4.60" flatter.

The .30-378 Wby. Mag. shoots a little flatter than the .340 wby. Mag., but that is about it. The .340 Wby. Mag. hasa little bit more energy than the .30-378 Wby. Mag. The .340 Wby. Mag. has a largerdiameter bullet than the .30-378 Wby. Mag. The ammo for the .340 Wby. Mag. isless expensive than the .30-378Wby. Mag.($27.00 difference in US),and that mightbea factor since you don't handload.

Good luck.