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-   -   Sighting for 100 yards when I only have 25 (http://www.firearmstalk.com/forums/f65/sighting-100-yards-when-i-only-have-25-a-104143/)

rfalls1891 02-18-2014 03:47 AM

Sighting for 100 yards when I only have 25
 
Just finished my first 300 Blackout build and mounted a Vortex Crossfire 2x7 on it. I was hoping someone could help me with a question I need answered before this weekend. If I only have the opportunity to sight my AR at 25 yards, how high above the POI do I have to sight the crosshairs on a paper target for it to be within less than inch between POA and POI at 100 yards? Any info anyone can provide would be greatly appreciated. :)

nitestalker 02-18-2014 03:54 AM

Try this.:)

http://www.shooterscalculator.com/ballistic-trajectory-chart.php?t=f630255c

c3shooter 02-18-2014 01:36 PM

Well, since you did not give us a HINT about what BULLET you are shooting, would suggest you start about 1 inch BELOW the aim point. The bullet is still rising to the line of sight on most AR type firearms. And I have seen 300 Blackout run from 120 to 240 gr bullets at different speeds.

nitestalker 02-18-2014 02:39 PM

Bullets rises when fired from a rifle? maybe? Bullets are rising down range? Not likely. Did Old Newton get his theory wrong? Or is this a long held shooting "Myth"?:)

http://www.chuckhawks.com/bullet_trajectory.htm

John_Deer 02-18-2014 02:59 PM

Depending on the height of your scope rings the gun is going to shoot at least a couple inches high at 100 yards if you sight in at 25 yards.

You are not wasting your time sighting in at 25 yards. If you have the rifle sighted in at 25 yards it will only require a few shots to get the rifle dead on at 100 yards.

seancslaughter 02-18-2014 03:02 PM

try this http://home.comcast.net/~j_colt123/25%20Yard%20Aimpoint%20100%20Zero.pdf

c3shooter 02-18-2014 03:17 PM

Nitestalker- bullets begin to drop the instant they leave the barrel- IF the bore is level.

However, as that article explains- almost every rifle will be tipped up to some degree. The bullets travel in an arc (a parabola) that passes upward thru the line of sight, and drops BACK to the line of sight at the target.

Except for my phased plasma rifle in the 40 watt range. It shoots flat. :p

nitestalker 02-18-2014 04:31 PM

That whole gravity thing is confusing .:D

yazul42 02-18-2014 04:39 PM

c3,,, is that plasma rifle legal for elk and what would be the minimum wattage you would recommend?

rfalls1891 02-18-2014 05:50 PM

Quote:

Originally Posted by seancslaughter (Post 1509435)

That is the perfect chart! Thanks for your input guys. :)


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