Advice on calculating Hold-over/under mil dot distances

[Brian.Samson]

Hey all,

I am fairly certain this post is in the wrong place but I can't post it anywhere else so do move if necessary.

I am looking for some advice on how people figure out the distance of each mil dot in their scope for making hold-over/under shots. Is it just trial and error test work or can a scientific formula be applied with relatively accurate results? If it is trial and error, what would the best setup be to do the figuring out? any advice offered will be greatly received.

The rifle and scope in question here are the HW100kt lam and the Hawke Airmax 30 4-16x50. I typically zero the scope at 25 yards to make working with MOA simpler, Having recently spent time learning about minutes of angle and how to zero a scope mathematically.

The problem with doing all of this mathematically, is that you'll end up making assumptions and entering incorrect values.

As an example - where did you get the BC for your pellet? - it will be an average that can vary massively from shot to shot, and from one batch of pellets to the next. The figures often quoted are average figures.

If you've read up about mathematically zeroing by minutes of angle - I guess you'll be making the assumption that your scope clicks actually are 1/4 Moa. They aren't.

Similarly when you go to using mildots, you'll probably be making an assumption that your scope has true mildots at 10x mag - it won't.

All that adds up to a whole heap of errors and assumptions - and it's the reason why people will often say that Chairgun is wrong. It can only be as accurate as the information it's being fed - Garbage In, Garbage Out.

Even zeroing by shooting at paper at set distances isn't foolproof - parallax error, cant, wind, poorly grouping pellets, bad technique, cylinder fill pressure, dirty barrels etc etc. Can have just a disastrous effect on the results as the errors and assumptions made in Chairgun.

[cooper_dan]

Even zeroing by shooting at paper at set distances isn't foolproof - parallax error, cant, wind, poorly grouping pellets, bad technique, cylinder fill pressure, dirty barrels etc etc. Can have just a disastrous effect on the results as the errors and assumptions made in Chairgun.

This!
If I zero at the beginning and end of a session they usually wont match up. It takes me 20 or 30 shots to get warmed up before I can worry about getting any good results.
I've started doing more regular holdover testing and will be keeping the data from all of them. Never hurts to have more information.