I got back out there today. Plan was to shoot a few at 8X scope power, then at 5x then 3x, then switch ammo from Remington to Nitrex. I wouldn't believe the results if I didn't see this myself.
First shot 8x @ 100 yds. Bullseye! Next two within 1" or so of the bullseye. Scope out to 3x. All on the paper but the group went out to about 4". I understand that because I can't see the target as well. Back to 8x. Two more near the bullseye with Remington, then a Nitrex. ...7-8 inches to the left! More Remingtons, right back on! Nitrex to the left! Go figure. I woul never have thoguht there'd be that much difference.

I wouldn't have thought that either. Are the bullets of the same weight though? The Nitrex bullets must be loaded much hotter is all that I can figure.

Quite often two different brands will shoot in completely different spots with the same weight bullet. Differences in powder, primer, even casings will make the gun shoot differently. Also I always sight in with my scope on the power that I most likely will be hunting with. There are some scopes that will shift point of impact when you change power.

Both were 165 grain bullets. Changing the scope from 8X to 3X didn't move the group. It just got bigger (less magnification, harder to see, I guess). Really weird, but I've done it twice now, so I'll stick with the one that is dead on. I'm sure if I adjusted my scope to move the Nitrex bullet to the right, I'd shoot as good with them. Go figure...

What you experienced is extremely common.

Tom

Even when handloading, when switching from one powder to another using the same bullet, primer and casing when working up a load quite often causes a noticeable difference in POI. Same can happen when keeping all the components the same but switching bullets wt. for wt. It is, indeed, common, like statjunk says.

You will find also that buying the same brand name with different lot#'s (dates manufactured) will 9 out of ten times shoot different POI as well.
Note: If you find something off the shelf that shoots well in your firearm, you might want to stock up with the particular lot #, the next lot may not work as well for you.

Two bullets of the same weight but with different manufacturers can have many differences that will have an effect on where they impact, or how they fly. ALL else being the same even.