Most powerfull cartridge option.

[Biggerhammer]

I hate efficient and buy powder in bulk. 👍

[JimmyHoffa]

Some of the bigger cartridges will require long barrels to burn enough of that efficient powder to get the performance the cartridge is somewhat designed for.  Could go with something like a .458 Win Mag and keep barrel length down, find ammo and have good bullet momentum which would out do that of smaller, faster bullets with 'high energy'.

[mountainman]

Some of the bigger cartridges will require long barrels to burn enough of that efficient powder to get the performance the cartridge is somewhat designed for.  Could go with something like a .458 Win Mag and keep barrel length down, find ammo and have good bullet momentum which would out do that of smaller, faster bullets with 'high energy'.

 

[Biggerhammer]

In a sporter weight, long action Remington 700. Factory chambering, the .375 Ultra Mag is pretty much the bad ass on the block. A 260gr Accubond on top of 102+ grains of IMR 7828 @ over 3000fps, crushes stuff. I know.

[wadu1]

In factory cartridges the 9.3x62 would be the most powerful, if you could find brass the 11.2x72 Schuler/Mauser at 5300 fp of energy would be tops it is a magnum case with a rebated rim so feed rails and everything but the bolt face would have to be openned.

Wildcats a 375 Whelen Improved or something like it on the 9.3x62 case would be about tops.

I'm a fan of the 9.3X62; it has been around a long time and still grandfathered in some African Country's as a big boy. For a off the shelf round since the early 1900s you can not beat it. If you are on a hunt in the Dark Content and all your ammo is lost in transit you still can get 9.3X62 you may not get any of the hot US stuff. Elk and Bear have fallen to my 9.3X62 with one shot. Like said the 9.3X62 is a little small for a T-Rex but over kill for a daisy.
 

[mountainman]

In factory cartridges the 9.3x62 would be the most powerful, if you could find brass the 11.2x72 Schuler/Mauser at 5300 fp of energy would be tops it is a magnum case with a rebated rim so feed rails and everything but the bolt face would have to be openned.

Wildcats a 375 Whelen Improved or something like it on the 9.3x62 case would be about tops.

I'm a fan of the 9.3X62; it has been around a long time and still grandfathered in some African Country's as a big boy. For a off the shelf round since the early 1900s you can not beat it. If you are on a hunt in the Dark Content and all your ammo is lost in transit you still can get 9.3X62 you may not get any of the hot US stuff. Elk and Bear have fallen to my 9.3X62 with one shot. Like said the 9.3X62 is a little small for a T-Rex but over kill for a daisy.
 

My good buddy uses a neat old double in the 9.3X62 and has slain everything in north America and most critters on the dark continent. He swears by it!

[mountainman]

375 ultras not a bad choice either. Thinking either that or the Lazzeroni on my next trip to S. Africa. But again, my little 308 did pretty good last time! Or...? A 338 Whelen in a light bolt would be the cats meow for a lightweight, hard hittting, efficient bolt gun! Especially for plains game.  And yes, mountainwalk, the 338 Ruger is an awesome caliber also! Especially in a light M77 Alaskan. Had one a few years back. Only pushed several boxes of factory thru it, but was eerily accurate!

[MountainWalk]

That 450-375UM seems like a blast!

All the wildcats seem like fun, but I need to be able to just buy ammunition. Even if I have to get it from cabela's. No credit card, so no online shopping. As for power, what I'm after is a heavy(250-300) slug and three hundred yard capability. I'd like to, if I can scrape together the jack to do it, to rebarrel it with a 20-22 inch tube. Thanks for the help. I'm kinda entertaining going back to the good old 338WM. I've still got good nosler handloads for it, I know the cartridge and I'm a firm believer in it, and ammo isn't too pricey. Still thinking about the 375 Ruger.  Anyone know much about the 358 STA?  Would it fit a standard length action?

[Biggerhammer]

The .358 is based on the 8mm Magnum case, yes it will work just fine on a long action. I owned a Rem700 8mm Magnum years ago but since the introduction of the Ultra Magnum line, it was no longer needed. The 358 STA is the 8mm Magnum necked up. With the powder capacity of the 358 STA and the majority of the powders used for reloading it. You would be selling the chambering a little short by going with your above mentioned barrel length.

[MountainWalk]

But out to 300, it prolly would't make much difference, would it Biggerhammer?

You would be selling the chambering a little short by going with your above mentioned barrel length.

[MountainWalk]

Reason for the short tube is packability and ease of moving around in the brush.  I'm not totally against the idea of a 458 either.... I know no elk alive needs that much hardware, but I really LOVE shooting the stiffer stuff.

[MountainWalk]

Update-

Going with 338 wm. Been looking at the Shaw barrels. A good barrel? How much should you expect to pay for a rebarrel job?

[mountainman]

Excellent choice Mountain! Keep us posted!

[Bwana Bob]

I had a 338/06 built in 1990 on a Ruger tang safety action, It sports a Douglas 22in barrel and a Bell& Carlson stock that has been glass bedded. I had it throat ed for the 225gr Hornaday bullet to just fit in the mag. I really saw no use in using a 250gr bullet in the 06 case, although it may be a good bullet in the dark timber. It shoots well under and inch even with the old style Barnes 200gr bullet, which is my main bullet for large game.
Its been to African 2 times where its taken 10 of the large African antelope, all being as large as an elk or larger, an eland.
It has accounted for a moose, four elk, two deer and 7 or 8 reindeer in AK. Its killing effect on game far exceeds its ballistics on paper.
I get 2820fps with those 200gr Barnes X's. My furthest shot has been 275 yd on a reindeer bull.
Its recoil is on par with a 300 win mag but much less than a 338 win mag , especially a light weight one. I love mine and will never sell it.
While this is not the most powerfull option, it's a good simple one, and an easy cartridge to load for. 

[yorketransport]

Update-

Going with 338 wm. Been looking at the Shaw barrels. A good barrel? How much should you expect to pay for a rebarrel job?

Good choice! I had Shaw put a 338-06 barrel on a Mauser 98 action for me years ago. Shaw may not make a match grade barrel, but my gun shot at least 1 MOA with the 225gr Partition, so that was perfect for a hunting rifle. Sold to a guy here on the forum a few years ago and he's still happy with it as well. I think it cost about $350 total to have them install the barrel.

Andrew