Great Question and many excellent responses. I own a 300 Weatherby Mag , Mark V Deluxe from the 1980's. 26 factory barrel. Glass bedded . I purchased the barrel from a guy "up grading " his 300 Wby. Mag to 340 Weatherby Mag . So I bought his 300 Wby. Mag barrel. So up until now the heaviest weight bullet I have ever shot out of that rifle was a 180 Grn bullet. This coming spring I will shoot 190 Grn. Accubonds and also try some 200 grn bullets. What I like k about my 300 Weatherby Mag is that if I'm going to the range and I just want to enjoy shooting this Hunting rifle, I can easily back off the load and shoot at 300 Win Velocities. Thats really simple. I even used to shoot it at 30 -06 velocities, Just for fun. So ,in my personal opinion, 2 excellent Big Game hunting calibers. No Question about that . Both are adequate for Elk, Moose, Bear, Caribou. Lots of African Plains game, too. I just think it's hard to beat the accuracy of shooting a carefully made and tested hand load, out of a properly bedded Weatherby Rife with a Muzzle break, and a properly adjusted trigger( or a High Quality Aftermarket Trigger) . I know a lot of guys are going to laugh at this, but if you will allow, this reduced load, shown below , was fired from my Weatherby Mark V , back when I did not even know how to adjust the trigger. Except for a twitch by me, its a nice 100 yard Groupe from a hunting rifle. I am getting this rifle ready in the hopes of a Penn Elk Hunt . I think the 180 Grn Partitions will be the bullet !!