Point of impact change with different bullets?

There WILL be a difference in your point of impact between two different cartridges, generally. That's true even if the weight of the bullet is the same. A Remington Core-Lokt will perform differently than a Winchester Super-X.

At 300 yards, you could miss completely. That's because different cartridges have the potential to cause the barrel of your gun to flex in different ways. Yes, your barrel flexes when you shoot the gun.

Watch the video in the first post here: http://www.armyparatrooper.org/dropzone/showthread...

Is 7mm Remington Magnum a suitable cartridge for moose? I wouldn't pick it. I'd choose something in at least .30-caliber, maybe .338-caliber. Moose are fairly heavily built, and while 7mm Rem Mag might do the job, I'd prefer to know beyond a shadow of a doubt that my rifle will do the job with the first shot.

Premium bullets are better than basic ones for deer hunting, but the difference isn't much. For moose, you want all the help you can get, especially when using a small bore like 7 mm. Not only do you want a premium bullet, you want one with more sectional density (160 grains). Yes, you'll need to shoot any new load at various ranges, not just to re-zero but to see how much the different ballistic coefficient affects your longer shots.

Sorry, but even with the best of the new bullet designs, you can't really expect optimum bullet performance in opening up on a broadside shot on a deer and also driving through all that heavy stuff in a quartering shot on a moose.

Power max may be better for Moosing and at 300 yards there maybe a few MOA difference. I would look at a trip to the range first.

the superx pp is alright but fragmants too much the powewr max is a better design it will retain alot more wieght which transfers more energy into the animal. there will be a small poi diffence but to be sure test an reset scope for that cartridge. anytime you change cartridge with one bullet to another or even mfr's you need to test.

Only way to be sure is to shoot both on the target.

300 yds is quiet a distance. 1/8 of a phart will make a big difference at 300y.

If they are the same weight and shape, I wouldn't expect any difference in trajectory/POI. the only difference I expect is possibly expansion and fragmentation. Like Space Cowboy says, take a box to the range and give it a shot.