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Discussion Starter #1
I am rechecking my scope's zero after a range sighting episode from hell, dont ask!

My question is if I zero my .308 shooting two inches high, 150 gr. bullets at 25yards, will this put me about dead on at 100 yards?

I don't have access to a hundred yard range. so I need to word this data out at 25 yards. Thanks!
 

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25-yard mid-range trajectory for a hundred yard zero would be below
the line of sight. The bullet is still 'rising' at that point.

To figure precisely, you need to know that mid-range trajectory, and
the height of your scope above the bore. Winchester's website does
show 50-yard mid-range trajectory, but not 25-yard.

I think if you sight in 2 inches high at 25 yards, you may be off paper
at 100.


Joe
 

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Joe is correct. At 25 yards your bullet should be impacting around 1.0 to 1.25 inches below line of sight - assuming 1.5 inches from centerline of sights to centerline of the bore. If point of impact is 2 inches high at 25 yards you should be roughly 8-12" high at 100 yards - depending on what you are shooting and how fast its going. Stated another way, if you wanted a 25 yard zero, you would need to come down roughly 8 MOA to get your zero from your current impact point.

Jeffvn
 

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Discussion Starter #4
I appreciate your replys so far

The only access to a 1oo yard range that I have is totally unsatisfactory, so I need to use the 25 yard figures to get as close as I can to being right on at 100 yards.

The bullets are 150 gr. Winchester power points and I dont know the BC. So in other words I should be about two inches low shooting at 25 yards because the bullet is still rising?
 

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The only access to a 1oo yard range that I have is totally unsatisfactory, so I need to use the 25 yard figures to get as close as I can to being right on at 100 yards.

The bullets are 150 gr. Winchester power points and I dont know the BC. So in other words I should be about two inches low shooting at 25 yards because the bullet is still rising?
That's probably too low. I'd suggest about an inch low at 25, IF your
scope centerline is 1.5 inches above the centerline of your bore. Your
POA should be between the centerlines. Exactly where is a GUESS.

Joe
 

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Discussion Starter #6 (Edited)
zero'd my rifle at 50 yards dead on

Someone posted a bullet trajectory graph that answered alot of my questions. I rezeroed the rifle right on at 50 yards, and according to the graph, my bullet should probably be about a inch high at 100 yards if I figured things out right.
 

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See ballistic table calculator at site shown below and create your own table for the bullet or bullets of your choice.

For my .308 shooting 168 grain Hornady Match bullets from Black Hills, the table shows the point of impact at 25 yards to be - 0.6 inches for a 100 yard zero.

This (-0.6 inches) should put you pretty close for your 150 grain bullet as well.

Good luck.

http://www.eskimo.com/~jbm/calculations/traj/traj.html
 

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See ballistic table calculator at site shown below and create your own table for the bullet or bullets of your choice.

For my .308 shooting 168 grain Hornady Match bullets from Black Hills, the table shows the point of impact at 25 yards to be - 0.6 inches for a 100 yard zero.

This (-0.6 inches) should put you pretty close for your 150 grain bullet as well.

Good luck.

http://www.eskimo.com/~jbm/calculations/traj/traj.html

You must also factor in the difference between the line-of-sight and
the bore. Trajectory alone will lead you astray.

Joe
 

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blackcoat is right on. my spreadsheet gives 0.65" low at 25-yds. This assumes:
1.5" scope height
150-gr sierra boat tail
0.423 BC
2700 fps muzzle velocity
600 ft above sea level
 
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