8x57 or 30-06?
Like with most of the similar cartridges under discussion in this series there is no valid argument that puts either of these two above the other. If I were to buy a new elk rifle and I look over the offerings and there is a piece in the shelves that attracted my attention by its impressive wood, and it shoulders well and the barrel is anything between 24"-26" and it is a Mauser or Mauser based action and the price is reasonable - and I see either .30-06 Sprg or 8x57 JS on the barrel I shall take it and know that it will do the job in exactly the same perfect fashion as the other would have.
The 8x57 shoots each bullet weight from 220 gr down to about 180 gr about 50 ft/sec faster than the 30-06 but the impulse per bullet frontal area of the two calibres is exactly the same, so penetration into a heavy animal with similar shot placement will be the same.
For me, personally, owning a very pleasing looking and accurate Musgrave 30-06 bought for the reasons mentioned right at the beginning of the article, an 8x57 JS Mauser in a Mauser 98 action and a Musgrave barrel will be a dream come true. Just because.