Interesting 270 win trajectory

sbe

sbe

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I am trying to figure out what is going on with my new 270. It is a Ruger american so only a 22 inch barrel and I am using Hornady Superformance ammo 130gr GMX - and it is grouping increadibly well (3 shots 1/2 inch) and is shooting very very flat. I have it set at 2 1/4 inchs high at 100yrds and at 200yrds it is 1.5 inchs high and right on at 300 yards.

I did this on two shooting sessions on two diferent days and I can not make sense of it as a 270 should not shoot that flat I am not sure how it is happening. I need to have a second shooter try and repeat this to make sure is is not something in the way I am holding the gun on rest.

I am trying to see if anyone else has ever had odd trajectories and know if how I hold gun on rests could do this - I don't want to get out on field assuming this is correct and completly miss what I am aiming at.

Thanks
 
Is the trajectory listed on the box.
130 grain Fusion shows 2.9 inches low at 200 when sighted in for 100 yards.
Your BC is .460.
Using this BC, the following figures were extracted from the Nosler No. 7 manual.
Assuming 2900 fps and a 300 yard zero, at 100 you would be 3.9 high and at 200, 4.6 high.
Similarly, at 3000 fps you should be 3.7 and 4.4 high at 100 and 200 respectively.
At 3000 fps and "0" at 200 yards, you would be close to 1.5" high at 100.
Were all your distances established with a range finder. The reason I ask is based on a range that most assumed was 300 yards, was actually 250 divided roughly into thirds.
My range is 100 and 200 metres with the 300 actually 297 yards. For practical purposes my sight in is at 220 yards. Using a chronographed velocity, most charts can be converted to a 220 yard trajectory so that the 200 yard figure is slightly high and the 300 yard figure will show 5 - 6 inches low depending on entering accurate information.
 
I see no problems with your situation. You're sighted for 300 yards and the bullet will definitely be higher at 100 and 200 yards as you described and drop down at 300..... the type of trajectory expected (arc shape) or did I read your situation incorrectly. You definitely have a very accurate hunting rifle.

After second thoughts, your trajectory appears to be much flatter than most 270 data seen on the Internet. Your ammo might be very special..... will check it out.

Pse see: http://www.hornady.com/store/270-Win-130-gr-GMX-superformance/ where I see a drop of 7 inches between 100 and 300 yds using a 24" barrel.

Good hunting!

Duke1
 
Last edited:
07blackwater said:
How high is your scope mounted? If it's higher than 1.5" (center of bore to center of scope) the published numbers won't be accurate.
Click to expand...

This is what I was thinking, but it doesn't make sense after looking at it again. His ballistics shows the bullet dropping only 1.5" from 200 to 300 meters???? something is not right.
 
Very odd indeed, I would reshoot and verify the results. The trajectory he is reporting is flatter than the 270 WSM, and many other calibers. Something fishy here..... sure they aren't 100 grains?
 
The scope is 1.5 inches above mid bore. I did not verify ranges but they are posted distances at my range. There was about a 30 to 40 k tail wind. It is a 130 gr bullet the box has the velocity listed as 3190 in 24 inch barrel (i don't think a 270win loses much in 2 inches so maybe 3000 to 3100) I did not have my chrony to test.

It does not make sense as a 300 yard zero would have the 200 yard higher than 100 yard. I don't shoot at 2 and 3 hundred yards often from bench and likely leaned harder on gun to hold it steady, I don't think I pressed down hard enough to change anything not sure if that is even possible and if I did it was consistent as 300 yard target had 3 shots in 2.5 inches.

It's a bit confusing to me.
 
stubblejumper said:
There is no way that you are driving that bullet fast enough to drop only 1-1/2" from 200 to 300 yards.
Click to expand...

I agree that's why I am trying to figure what might be going on it must be something in my technique on bench but I don't if it's possible as the barrell is free floated but the stock is not very stiff.
 
Something is amiss. Even at 3500fps 2.5" high@100, it would be 3"high@200 and zero@300. Yours is not even following a physically possible trajectory.
 
is it possible that you are resting on the barrel instead of the forehand?
my uncle,a couple years ago, was wondering why is 7rum was sometime dead on
at 250y and other times he was 14" higher (yes 14", not 1.4")
i noticed he was unknowingly alternating between barrel and forehand on the front
rest.
resting on the forearm only solved the problem
 
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