Zero In and setting up a Trajectory Plot Chart

"zeroing-in" or "sighting-in." is the action of adjusting sights so they are properly aligned with the point of impact.

This article assumes that you are using a Mil Dot type scope (or similar multi aim point scope which are relatively commonplace these days)

Set up a Trajectory Plot using the example at http://www.erifle.co.uk/resources/Mil%20Dot%20Trajectory%20Plot.xls 
Ideally you will have access to land with enough safe distance and effective backstop to set up the ranges you will need to shoot over.
Wind can affect pellet point of impact and therefore the most calm of conditions will be an advantage.

Set up a target that enables you to take multiple shots and have visibility of the point of impact of each shot.
Measure out your preferred Zero-in range (For example 12 yards).
Take a number of shots until you are happy that you have enough to see a true "average point" within the group.
Adjust your sight to zero-in your centre cross hair / Mil Dot to the true "average point" within the group.
Repeat a number of shots until you are happy that you have enough to see a true average point within the group and readjust until you are satisfied that the centre Mil Dot is consistently at the average centre of the group.

Measure out your next range (For example 15 yards).
Using your centre Mil Dot take a number of shots at a specific target point until you are satisfied that an effective average group is achieved. Note - don’t move your point of aim. Instead continue to aim at the same target point building up an average group of impact points that will usually be above your point of aim (In this example). Note the centre of the group in relation to your Mil Dots and mark this point on you Trajectory Plot Chart.

Continue to measure out additional ranges from your minimum to maximum ranges and repeat the above.

Build up a number of marks on your trajectory plot chart for various ranges.
Note - that the more ranges and hence points on your Trajectory plot chart, generally the more accurate your final trajectory plot chart will be.
You will be able to join the dots in a sketched curve fashion to fill in (extrapolating) any missing ranges and to provide a "smooth" plot from you minimum to maximum range.

This is a rough guide to setting up a scope-rifle combination.  If you would like to provide constructive comment to help build up a better guide or submit your own example guide to this or other Airgun sport areas - all contributions will be gratefully received and duly credited to you.

Thanks

erifle Admin

admin@erifle.co.uk