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Old 01-31-2010, 04:15 PM   #1
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Default 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.
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Old 01-31-2010, 04:46 PM   #2
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not adjusting the scope, my groups were 5" higher. Is this what should have happened?
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.
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Old 01-31-2010, 05:02 PM   #3
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It's only fair to compare drop one at a time, re-zeroing for each.
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Old 01-31-2010, 05:20 PM   #4
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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.
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Old 01-31-2010, 06:08 PM   #5
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Originally Posted by Cut'em Jack View Post
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.
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Old 01-31-2010, 06:30 PM   #6
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pressures and velocity affect the harmonics of the barrel

When you pull the trigger the pressure behind the bullet creates a vibration of the barrel, some say the muzzle moves in a circle some say a figure 8 but it does move, now depending on the pressure and the velocity is what determines where the muzzle is in its harmonic travel when the bullet exits the barrel. This is what determines the POI with different bullets. this also determines how your rifle will group, if the bullet exits the same time, same placein the harmonic travel at the same velocity then the bullets all land in the same place on the target (if you do your part).
You can dramaticly change group size by something as simple as seating dept as that changes where in the harmonic travel the bullet exits the muzzle.
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Old 01-31-2010, 08:57 PM   #7
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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
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Old 02-01-2010, 01:09 AM   #8
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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.
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Old 02-01-2010, 05:12 AM   #9
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Originally Posted by VAhuntr View Post
Not always the case either. I have seen heavier bullets actually hit higher many times due to increased recoil.
All things being equal, you would expect a heavier bullet to drop quicker, that's just basic physics.
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Old 02-01-2010, 08:47 AM   #10
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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.
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