# 7mm Ballistic Question



## Igottabigone (Oct 4, 2007)

All right, I am confused. I am wondering what is the height in inches that I should be impacting the target at 25 yards. Or should I be hitting dead on at 25yds. I was always taught that 25 yards was the first place that the bullet crosses the line of sight, but now that I think about it that was with an .06. So if my bullet is 1.5 inches high at 25 yards what is my zero point, the distance at which it crosses the line of sight. I am shooting factory loaded 150gr. bullets. I basically want to know what my gun is sighted in for. I look at all the ballistic tables and they talk about MOA and stuff. I want to know in inches. I know the 7mm shoots very flat so it can't be that much of a difference. Any help?


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## reb8600 (Sep 8, 2007)

You dont say how far you want to be sighted in for so I will assume you want 100 yds. Your point of impact should be about 5/8" low at 25 yds. If you are 1.5" high at 25 yds you are sighted in for about 550 yds. MOA is minute of angle. 1 MOA is 1" at 100 yds, 2" at 200 yds etc.


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## Igottabigone (Oct 4, 2007)

So if I want to be sighted in for 300 yards where should I be hitting at 25 yards?


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## DallanC (Jan 13, 2009)

Any theoretical discussion on ballistics without knowing your bullets ballistic coefficent and its muzzle velocity is worthless. Too many variables to guess on. Being the author of a computer ballistics calculator, this is one thing I know alot about 


-DallanC


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## NHS (Sep 7, 2007)

Igottabigone said:


> So if I want to be sighted in for 300 yards where should I be hitting at 25 yards?


If you want to be sighted in for 300 yards, my advice is to go shoot at 300 yards.


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## reb8600 (Sep 8, 2007)

NHS said:


> Igottabigone said:
> 
> 
> > So if I want to be sighted in for 300 yards where should I be hitting at 25 yards?
> ...


He is giving you good advice. Shooting at 25 yds is good for getting you on paper but does not work to sight in accurately for any other distance.


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## Gumbo (Sep 22, 2007)

Mo


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## Loke (Sep 7, 2007)

The best advice will be to shoot targets at the distance you will be shooting game. The best targets are the ones that don't stand still and wait for you to shoot. In the practical world, there is not enough difference between your 30-06 and 7mm to worry about. Go out and shoot a bunch to get familiar with whichever one you are going to hunt with.
There are too many variables to say "your rifle should be dead on at this short range to hit dead on at this longer range". Ballistic coefficient and muzzle velocity are the two most talked about. Then you need to add in the height your sights are above the bore. This will vary with each rifle, mount, and scope combination. My advice is to shoot your rifle at whatever range you want to sight for. Then shoot at shorter and longer range and record the results for future reference. I will guarantee that they will not match up perfectly with any ballistics chart anywhere. There will be minute differences in the way your rifle shoots your particular load. It may be better or worse than the rifle used to collect the data in the ballistic programs.


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## DallanC (Jan 13, 2009)

Yea I was going to come back and mention the scope height (if there is one lol).

Virtually any modern medium bore rifle (270/308/3006/7mm etc etc) has a pretty nice trajectory, all things concidered. A roughly 300 yard zero will mean you get a PBR (point blank range... means you dont need to compensate for drop) out to about 325 yards. The highest point will be roughly 3" above line of sight.

Get a good ballistics calculator (free: www.HuntingNut.com) and run your own numbers for specific results.

Above all though, as I tell everyone and has been mentioned above: If you want to know where your bullet hits at X yards you have to go shoot it at X yards!!! Ballistics programs are great for "what if" senarios on a rainy day, but its no substitution for in the field testing.

-DallanC


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## Igottabigone (Oct 4, 2007)

Good advice fellas. I appreciate it. 

Dallan,
If my rifle is zeroed in for 300, at what distance will my bullet cross the line of sight first? I guess that was what my original question was. Will there be a big difference between a nosler partion, silver tip, core lokt, etc in 150gr?


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## DallanC (Jan 13, 2009)

Igottabigone said:


> Good advice fellas. I appreciate it.
> 
> Dallan,
> If my rifle is zeroed in for 300, at what distance will my bullet cross the line of sight first? I guess that was what my original question was. Will there be a big difference between a nosler partion, silver tip, core lokt, etc in 150gr?


To know that, I would need your bullets bc, muzzle velocity and the height from the center of the bore to the center of the scope.

On my site, HuntingNut.com I have both a PC ballistics calculator for download as well as a online version with graphical output for registered members (free).

The free online calculator is at:

http://www.huntingnut.com/index.php?nam ... lankOnline

-DallanC


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## bullsnot (Aug 10, 2010)

Igottabigone said:


> Good advice fellas. I appreciate it.
> 
> Dallan,
> If my rifle is zeroed in for 300, at what distance will my bullet cross the line of sight first? I guess that was what my original question was. Will there be a big difference between a nosler partion, silver tip, core lokt, etc in 150gr?


How exact do you want? It will be between 20 and 25 yards. If you need to know exactly then zero at 300 then and play around at different ranges to find it. My recipe is 150gr partitions with 62 grains of IMR 4831 for my 7mm Rem Mag and I am zeroed at 300.


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