RLH,
The reason I don't compare the 150 grain .308 bullet with a 154 grain .284 bullet is because of the difference in the Sectional Density. This number is what you can look at to see the bullets that most resemble one another in different calibers. I am work right now so I can't read the exact numbers, but what I quoted earlier is what I remembered from last night.
Given equal Sectional Density and bullet types (ie Nosler Partition .284 140 grain vs Nosler Partition .308 165 grain or Hornady Spire Point .284 154 grain vs Hornady Spire Point .308 165 grain bullets etc.)you will get approximately the same amount of penetration, the same amount of ballistic drop or trajectory. That is why you compare the 139 grain to the 165 grain or the 154 grain to the 180 grain. They are the bullets with the most similar Sectional Density, thus they fly most similar and penetrate most similarly.
I don't know if this makes sense or not. That said, a bullet with a higher sectional density will actually fly flatter than one with a lower sectional density, over time. Sometimes this happens rapidly, sometimes it takes several hundred yards before this occurs. There are many factors playing a role. A bullet with a higher SD and a good BC (ballistic Coefficient) will buck the wind better, retain a larger percentage of energy through flight, and therefore maintain its trajectory more evenly.
A 154 grain 7mm Spire Point bullet has a higher Sectional Density and a higher Ballistic coefficient than the Hornady 150 grain .308 Spire Point bullet. This means that if pushed at the same velocities, the 7mm would fly flatter and maintain higher fpe. Are you sure you want me to compare the 150 grain .308 bullet to the 154 grain .284 bullet?
Like the original question was asking, Would you use a 7mm-08 for elk? It wouldn't be my first choice. If I was buying a rifle for elk explicitly, it would not be a 7mm-08. I would buy a .338 Win Mag. But will it do the job? Absolutely.
As far as where in the chain of 7mms does the 7mm-08 fall, you have to ask whether you are handloading or using factory ammo. With factory ammo, the 7mm-08 will outperform the 7x57 mauser, and be neck and neck with the .280 Remington. This isn't the cartridges fault. More the fault with poor and weak actions that had been used in the past and the factory ammo has to be loaded with those rifles in mind. With handloading, the .280 Remington will gain between 100-200 fps on the 7mm-08. The 7x57 mauser will sometimes eak a little more particularly in the "heavier" bullets due to a little more powder space which helps when seating heavier (longer) bullets.
Anyway, anything the .308 Winchester will do the 7mm-08 seems to do a touch better. My 7mm-08 used to be a .243 Winchester. Don't get me going there, but I was never convinced of any reason to have a .243 Winchester. Probably a lot like how you feel about the 7mm-08.
I feel like I need to defend this little cartridge as I am really becoming more and more impressed with it all of the time. It is a great deer cartridge. I would hunt elk with it if I had to, but I don't so I won't. FWIW that is my thought.
Firehawk