Zeroing for 200 yards with only 100 yards range to use.

Thank you all. I appreciate the knowledge transfer and information I get from people here, both hyper technical (I'm learning) and in laymans terms (I understand it).

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Originally Posted by newcastle

Do you have any more of those graphs that would show trajectory for 3" above POA at 100 yards for the same ammo. Even better would be interactive so you could drag the trajectory to allow for your 100 yard Zero. just to check, but is there ANY reason the same would not work for a No.1 Mk 3 if I used on of those instead?

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The figures and graph supplied are all you need for the problem initially posted. Just zero to put center group 6" above POA at 100 yards and it will also be very close to 6" above POA at 200 (with standard MkVII ammunition). If you want to do more ballistic calculations, see any of several online ballistic calculators - such as JBM's at http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi

In most discussions I've seen, the G1 ballistic coefficient for the .303 MkVII projectile is usually pegged somewhere between .420 and .470. At the short ranges involved in this exercise, there is minimal difference in results with either figure.

Sample output from Hornady's calculator at Ballistics Calculator - Hornady Manufacturing, Inc - slightly different parameters, same result!

Your Input Variables

Ballistic Coefficient	0.45	Velocity (ft/s)	2440	Weight (grains)	174
Maximum Range (yds)	300	Interval (yds)	100	Drag Function	G1
Sight Height (inches)	0.9	Shooting Angle (degrees)	0	Zero Range (yds)	282
Wind Speed (mph)	0	Wind Angle (degrees)	90	Altitude (ft)	0
Pressure (hg)	29.53	Temperature (F)	59	Humidity (%)	0.78

Ballistics Results

Range (yards)	Velocity (fps)	Energy (ft.-lb.)	Trajectory (in)	Come UP in MOA	Come UP in Mils	Wind Drift (in)	Wind Drift in MOA	Wind Drift in Mils
Muzzle	2440	2300	-0.9	0	0	0	0	0
100	2254	1963	6	-5.7	-1.7	0	0	0
200	2076	1665	6	-2.9	-0.8	0	0	0
300	1907	1405	-2.1	0.7	0.2	0	0	0

Usually if I dial in the theoretical change the POI ends up being higher than expected from 100 to 200yds. After that it's rarely high when the normal adjustments are made. Just why this occurs? Sorry! I've just learned to add about half of what is needed and let fly. Doesn't matter if it's scope or irons.