Thread: Difference between ballistic chart and real word results

Originally Posted by caberslash

Suspect the reticle on the EL Range is not exactly dead centre of where the beam is hitting.

Try getting your binos really stable, rested on something so you are not physically holding them up. A tripod is ideal but can be done with a backpack.

Now, range a very definite target which is only slightly bigger than the reticle, and nake sure its dead centre. Then turn your binos upside-down, and sideways, and repeat.

If you arr getting wildly different readings, keep trying using different areas of the reticle (12 oclock, 3, oclock, 6 and 9) until you get a more consistent reading.

Been seeing this quite a lot with rangefinding binos, even top end ones. Much prefer a dedicated handheld unit as they are much less prone to this issue.

Anyway, very simple ballistic chart.

If you have a rifle shooting a projectile with a 0.5-0.6 G1 BC and a muzzle velocity between 2,600 to 2,800 fps, the following should apply with a scope in Mils.

100 yard zero

200 yards 0.5 Mils

300 yards 1 Mil

400 yards 2 Mils

500 yards 3 Mils

600 yards 4 Mils

You might have to adjust between 0.2 to 0.3 mils (usually add) at 400 yards plus, but usually this is very close.

With your setup, I'd say the call of 7.5 MOA is more likely to be correct for 400 yards vs. 6.25, to make it easier, refer to this quick MOA to Mils chart:

https://docs.google.com/spreadsheets...mFqIo/htmlview

So, to keep it simple, potential list of issues, in order of likelyhood:

1. Your binos are not ranging correctly

2. Your scope is not dialling accurately, is it a Leupold...?

3. Your zero is off

4. Your chrono data is off (unlikely as it sounds about right with your setup).

Scope height only affects maximum point blank range, not the external ballistics of the bullet, and is a subject best left for now.

Greetings,
Some very good points in this post. Thanks @caberslash. Checking the accuracy of the readings from a rangefinder may not be as tricky as it sounds. Our local Council plus many others has a GIS system for land information which is available on their web site website. This includes Cadastral info, property boundary measurements and such plus aerial photos with decent detail. Ours also has a distance tool that allows you to measure the distance between two points with a couple of mouse clicks. I use it quite a bit so have a look on your local Council web site to see what is on offer. I checked the length of one of our boundaries which is a little under 400 metres with the distance tool and found the latter to be quite accurate. You may also be able to use the GPS coordinates on the GPS app on your bat phone to check the distance but this may need some Geometry to calculate. Have not tried this one yet.
Regards GPM.