270 maxed out with 140 NAB's is closer to a 7RM with 160's than one might think. At 500, the 7 RM has 3" less drop, 2" less drift, 100 FPS faster, and an additional 335 FPE, for whatever that's worth. I have a feeling only the chamber really knows the difference.
And of course, the experts.........
No experts here
Ballistic improvements come grudgingly. In a crowded field with bullets separated by a few grains,velocities by 100-300 fps,it's easy to look at tables and say not much difference.
It's often been said that the difference between some standard and magnum cases in a given caliber is 50, maybe 100 yards.
More importantly maybe,if we figure bullet expansion requires,say, 1900 fps,we see the 7 Rem Mag with a 160 AB will stay above that threshold to 700 yards,while the 270-140 AB example is all done at 600 (rough figures but you get my drift).
Feed the 7 Rem Mag something like a 162 Amax (some Bergers?),and we're still above 1900 fps at 800 yards.Those high BC boys know whereof they speak when it comes to stretching things out.
Not factored in is the generally faster twist of the 7mm barrels,coupled with higher velocity,both of which contribute to bullet expansion.But the tables won't tell us that.
In real life, I've fired enough (say) Bitterrots weighing 130,140,160,165 grains from various standard and magnum cases to say that the magnum cases expand those bullets better at 300 yards and beyond. This is definitely the case comparing the 270,280 and 7 Rem mag;and the 300 Win Mag vs the 30/06.
Even if we don't shoot beyond 500-600 yards,the advantage is there whether we need it or not.
There are solid reasons that 7mm magnums are pretty popular LR elk cartridges.It's mechanics as much as anything else.The faster a bullet is going when it hits something, the more it's going to expand
