We're talking about two very similar cartridges. .0.007" difference in bore diameter and both long action. There are a few differences. The most notable is twist rate - 1:10" for .270 vs. 1:9.5" for 7mm mag typically. That may not seem like much, but it does mean the heaviest flat base bullet that is all-altitude/temp stable in .270 is the 150gr, whereas in the 7mm mag it's the 175gr. Elk are pretty good sized critters (400 to 750 lbs generally, up to more than 1000 for Roosevelt elk). You'd really like pass through bullet performance on side and quartering shots. That means sectional density is a good thing, and that gives a small but noticeable edge to the 7mm mag.

While both cartridges have similar velocities for similar weights when loaded to SAAMI max, .270 is generally not loaded to max in commercial ammo. That's because .270 relies on higher pressure, while 7RM relies on case capacity. Manufacturers are leery of pushing the pressure envelope in the .270 and load it down.

For your friend, my take is you would see very little difference between the 160 7mm partition and the 150 .270 partition as they have very similar sectional densities. But you might see some improvement moving up to the 175 class in 7mm. I would also look at using the A-frame instead of the partition. The partition shines in situations where impact velocity may be low - the soft lead tip will open up well below 2000 ft/s. But at higher velocities it sheds a lot of mass which reduces penetration. The A-frame is bonded and has a harder front section. It needs an impact velocity of at least 2100 ft/s, but won't shed much mass no matter how fast your drive it and pretty much guarantees an exit wound (and thus something to track if need be) on elk. For that reason I like A-Frames. I shoot the 175 A-Frame in a 7RM on elk and have had excellent results. I used to use the 175 partition, and had good results but not as good.

I haven't used the Barnes and can't speak to them, but they're well thought of. A 150gr barnes in .270 is probably not all-altitude/temp stable - too long.

Either will work, but if the 7RM doesn't beat him up I would definitely have a preference that way.

Last edited by Llama_Bob; 05/27/17.