Is Chris Costa wrong? Any physics majors in the house?

SA Justin

Member
Apr 25, 2013
183
16

At about the 58:15 mark. The explanation on holding left or right... Maybe I'm confused but is he saying gravity tilts when you tilt and all of a sudden the bullet drops left or right?

Correct me if I'm wrong but as long as your windage is dialed in, you would still hold high or low depending on the distance. Never left or right, right?

My head hurts....
 

Mic

TGT Addict
TGT Supporter
Jan 3, 2009
2,835
48
Austin
No, what he is saying is that because the optics or sights are above the axis of the barrel, it will throw off your point of aim/point of impact.
When you are shooting normally and your target is closer to you than the distance the rifle was zeroed at, the bullets will be below it. When you get the gun sideways, this moves with you. It's the bore axis vs sight axis, not gravity.
 

SA Justin

Member
Apr 25, 2013
183
16
No, what he is saying is that because the optics or sights are above the axis of the barrel, it will throw off your point of aim/point of impact.
When you are shooting normally and your target is closer to you than the distance the rifle was zeroed at, the bullets will be below it. When you get the gun sideways, this moves with you. It's the bore axis vs sight axis, not gravity.
Thanks for the explanation. I gotcha.

Interesting... I'll have to remember than if I ever want to shoot a zombie while spooning with a hot chick. :)
 
Last edited:

Acera

TGT Addict
Jan 17, 2011
7,623
36
Republic of Texas
He talks about a 50 yard zero, but if I remember correctly did those guys not promote a 36 or 38 yard zero for ARs at one time??

Had a video of something like that but can't find it now for some reason.
 

Renegade

SuperOwner
Mar 5, 2008
8,307
113
Texas
What he is saying is if your gun has a 50 yd zero and you are closer than 50, your POI is lower. Let say 1/2 inch. I think we all understand that.

If you rotate your gun 90 degrees right (ejection port is facing down), the rounds will still be 1/2 inch low, but to the left and you need to compensate for that.
 

Renegade

SuperOwner
Mar 5, 2008
8,307
113
Texas
He talks about a 50 yard zero, but if I remember correctly did those guys not promote a 36 or 38 yard zero for ARs at one time??

Had a video of something like that but can't find it now for some reason.
I am not an uber cool instructor, but I promote a true BSZ and that depends upon sight height and MV. That is usually in the 40-44 yard range for a typical AR shooting M193 and Aimpoint 2.6 inches high.
 

Acera

TGT Addict
Jan 17, 2011
7,623
36
Republic of Texas
I am not an uber cool instructor, but I promote a true BSZ and that depends upon sight height and MV. That is usually in the 40-44 yard range for a typical AR shooting M193 and Aimpoint 2.6 inches high.
Actaully I have found some stuff on it, it was Travis Haley talking about a 36 yard zero for ARs with red dot sights. Seems that distance is a pretty good set up for multiple shooting situations/ranges likely to be faced with during an encounter. Can't find the video, but find references to it.............

GoogleFu is broken with me tonight :(


I can find the thread here I posted when it first came out, but the video link is wrong now.
http://www.texasguntalk.com/forums/rifles/39709-ar-carbine-zero-distance-video-print.html
 
Last edited:

Renegade

SuperOwner
Mar 5, 2008
8,307
113
Texas
Found this, one of the best depictions of how sights work I have seen. Lots of new folks don't understand this.




Shamelessly stolen from this good thread on the subject over at M4Carbine.net
AR-15 Zeros and Trajectories

Molon has done some excellent writeups on this and mean radius.
 
Top Bottom