30-06 150 vs 180gr trajectory
 

Today I decided to try a different weight round in my Savage 111. I've been shooting 180 Federals, but thought I'd see what a different weight round would do "range wise". My rifle is zeroed at 100 yds w/ 180 (made a triangular "keyhole" in the 10 ring today with a cooler as a rest). With that result I put in the only other round I had avail. (150 rem. core-lok)...not adjusting the scope, my groups were 5" higher. Is this what should have happened?
I personally believe this is correct, but according to the animated Winchester Ballistic site, the 150 and 180 should impact close to the same point @ 100 yds. This is not what occured today; albeit two different ammo manufacturers. Any input would be appreciated.

Any time you change bullets you must sight your rifle in again. That bullet could have impacted left, right, up, down or a combination of. No two bullets impact the same (usually).

After you sight your rifle back in again with the new bullets then the trajectories will be similar.

It's only fair to compare drop one at a time, re-zeroing for each.

You would expect the lighter bullet to be higher, however don't mix ammo and expect consistent results. I've never experienced left and right differences, only vertical.

Not always the case either. I have seen heavier bullets actually hit higher many times due to increased recoil.

Could be your Savage doesn't like 150 grain bullets. My Remington 700 doesn't like 150 grain-------5 shot group will cover a saucer plate. But with 180 factory's it will cover a Kennedy half dollar. With handloads it will cover a quarter. So I shoot 180's at everything. CB

I agree with what others have to say. You have to resight in for the new load, it is hard to find two loads that impact the same. On that note the flatter shooting round may not hit higher at 100 yards for a very good reason. The ballistic arch for a flatter shooter cartridge will be more stretched out. So sometimes at 100 yards, the heavier bullet with a worse trajectory will be further into its arch and be closer to its peak or highest point, thus making it impact higher at 100 yards, while the flatter shooting 150 grain is not anywhere near its peak point yet and is still climbing. I notice this a lot at 100 yards since it is not really close to the peak of flatter shooting trajectories.

All things being equal, you would expect a heavier bullet to drop quicker, that's just basic physics.

Since we're talking 100 yards and bullets going 2700-2900, bullet drop isn't the main factor here. It's just variances between two different loads.

It's all about the barrel harmonics of the different load. The 180 grain certainly doesn't experience 5" more drop at 100 yards than the 150 grain.