I always get into trouble with other internet users when I post my experiences with a custom 7x57 I had built a few years ago. It had a factory Lothar Walther barrel with long euro throat. I could list the dozens of loads I tested and used on game over years of use, but found my experiences did not match some of the accepted 'wisdom' that exists on the internet. I used a lot of different projectile weights from 135 - 175 on game.

It is a perfect deer rifle up to and including Red deer. I would say it is a perfect red deer cartridge and that is its niche. I loaded a conventional 140 Sierra SP at a measured MV of 2,641fps in my rifle. You won't go wrong with this projjie, especially if shooting out to 300 meters. Learn its trajectory and don't rely on ballistic tables in a book.

If you use it on larger game, the toughest projectile I would use would be the 154 Hornady and keep ranges quite short. I didn't try the 139 Hornady Interlock but should have. I did have great results with the first rendition of 135 ACP's on camels, but they are no longer available.

It is not a high velocity power house. Premium construction projectiles like Woodleighs will often fail to expand and/or pencil through. If you load heavy projectiles like a 175 of any construction, my experience is they will usually tumble at ranges beyond 150 metres due to a lack of impact velocity.

Summary
1) The 7x57 in my experience is not a long range or large game rifle.
2) Like the 9.3x62 (which I've also owned and used in Africa and on feral camels in the outback) it made its reputation with conventional projectiles and works best with those designs.