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Ballistics apps and wedges

Printed From: Kiwi Airgunners
Category: Technical
Forum Name: Pauly's Technical Area
Forum Description: Technical information, Modifications and DIY projects are all in here
URL: www.kiwiairgunners.co.nz/forum_posts.asp?TID=1270
Printed Date: 06 Dec 2025 at 6:43pm
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Topic: Ballistics apps and wedges
Posted By: kruzaroad
Subject: Ballistics apps and wedges
Date Posted: 13 Oct 2025 at 9:44am
Righto all you scope savy ppl heres a couple of questions that im uncertain about and going to look for answers here first.
A: Scope wedges add angle, does this mean that the apps need that info to adjust or does scope height cover that?
Being that the front of the scope is now a hair lower.

Being that chair gun doesn't have that angle to add, if adjustment for wedges is needed would setting the app as per usual, then using the angle the wedges are set too, put that number of degrees in the angle of up or down shot box, to get the correct compensation for a level shot?

I've got lots of pellets over three brands, all together but are running critically low each brand hw actually likes.
Don't want to waste pellets with actual shot data till fine tuning.
Have to get dial info on all three pellets again, plus for a thousand of a differnt brand sorted and stored for emergency.
Lots to get back on line, and it all starts with the scope.


Replies:
Posted By: mercs
Date Posted: 13 Oct 2025 at 10:52am
Hi Kruza, quick look at three on-line ballistics calculators and only the scope height was required.

Shims: I only use the Hawke 25MOA inserts and they are tapered as a matching set, references seem to indicate height at the reticle will alter with distance between mounts. Standard distance of 3.5 inches is used.

The examples show the MOA altering from 24.06 MOA at 3.5 inches to 16.85 MOA at 5 inches which would be 7 MOA x 4 = 28 clicks on most scopes. Seven inches at 100 yards which surprised me.


FROM Google AI Search

Hawke 25 MOA scope shims calculation
A Hawke 25 MOA scope shim adds a fixed 25 MOA of elevation and does not require complex calculations for its intended purpose
. The shim simply tilts the scope downward, which moves the center of the reticle to the upper end of its internal elevation adjustment. This provides more "up" elevation for long-range shooting. 

For standard Hawke Match Mounts with a 90mm (3.5 inch) spacing, the 25 MOA shim is designed to work correctly right out of the package. However, the actual change in MOA will vary slightly based on the distance between your scope rings

How to calculate shim effect based on ring spacing
You can calculate the exact effect of a shim if your rings are not set at the standard 90mm spacing. The basic principle is using geometry to determine how a small change in height over a horizontal distance translates to a change in angle (MOA).
The formula for MOA is based on the relationship that 1 MOA equals approximately 1.047 inches at 100 yards. The formula can be simplified for calculating shim thickness: 
Thickness needed for 1 MOA = (Distance between rings in inches) / 3600. 
Since a Hawke shim kit provides a fixed thickness for 25 MOA, you can use a rearranged version of this formula to determine the precise MOA added for your specific ring spacing:
Total MOA added = (Shim thickness in inches / Distance between rings in inches) x 3438
Note: The number 3438 is the constant for converting radians to MOA.

Example calculation
Let's assume the Hawke 25 MOA shim has a thickness of approximately 0.0245 inches, which corresponds to 25 MOA at the standard 90mm (3.54-inch) ring spacing.

If your rings are spaced 5 inches apart:
Total MOA = (0.0245 / 5) x 3438
  • Total MOA = 0.0049 x 3438
  • Total MOA = 16.85 MOA
  • If your rings are spaced 3.5 inches apart (close to the standard 90mm):Total MOA = (0.0245 / 3.5) x 3438
  • Total MOA = 0.007 x 3438
  • Total MOA = 24.06 MOA

Posted By: kruzaroad
Date Posted: 13 Oct 2025 at 12:18pm
Sweet mercs.
Good info indeed.
I never even knew that you could use the measurement between the two rings.
I'll have muck around with the info see what i come up with with maths while the wind persists.
Cheers

Posted By: Pauly5
Date Posted: 13 Oct 2025 at 10:09pm
I would think that by entering the scope height in relation to the bore is enough. That, along with zero distance and ballistic data provides everything that is needed to calculate POI for you.

But agree all that math is fascinating. 

Posted By: RangerPete
Date Posted: 14 Oct 2025 at 8:06pm
Kruza, I wouldn't worry about adding scope angle into a ballistic calculator or app.
Just get the scope to a usuable angle and try zero it at your chosen distance with the reticle as close to centered in the scope as possible.
Once you have zeored your rifle/scope combination, just use the app or ballistic calculator as normal.

-------------
Walk quietly, but carry a big stick.

Posted By: Pauly5
Date Posted: 14 Oct 2025 at 10:18pm
I used to think the BC should never be changed, but after tuning in a couple of digital scopes with ballistic info I have learnt that the bc changes, and sometimes you have to change the BC to match real life data.

Posted By: kruzaroad
Date Posted: 14 Oct 2025 at 11:01pm
Gees pauly i already killed one chrono doing muzzle volicity, let alone shooting at 60m to 80m to pass a pellet through one, for target volicity.😁


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