Chairgun/Strelok, scope zoom, range cards, and a partridge in a pear tree

[7weight]

Hypothetical question time.

If I'm using Chairgun and/or Strelok, have entered all the specs* correctly into each application, using a quality second focal plane scope and quality regulated PCP air rifle with shots grouping nicely at 30 yards, can I:
- assume the rifle will hit bullseye at 30 yards regardless of zoom power?
- get the apps to generate range cards at different zoom powers, and they be correct? Obviously, the zoom power would need to be modified for each scope zoom powers' range card.


*pellet, scope, ftps @muzzle, zero'd @ 30yds, etc

[45Bravo]

Never assume anything, at least try the different settings, BUT,

Since you normally sight in a scope at max zoom, (most people do so they can see the pellet holes) and then back off the zoom for offhand shooting.

If you are sighting in with point of impact for the center of the crosshairs, I would say yes.

If you are sighting in with hold over/under then no.

Now that being said, SOME scopes have some degree of variation in the position of the crosshairs as you go through the zoom range.

Not all scopes have that issue, but some do, I have seen expensive ones with the issue, and cheap ones.

With manufacturers now making scopes designed for airguns, they know the accuracy potential, and the customers expectations for repeatable zero throughout the zoom range, you see less and less of it.

I have used Chairgun to generate range cards, but only at a fixed zoom setting.

On my Hawke 3x12, I always use 6x for hunting, and that’s the card inside my rear scope cover.

[Gear_Junkie]

I have yet to have Chairgun match reality, no matter how accurate my data has been.  I always end up shooting at all of the various distances to get my actual holdover at each distance.  Sorry, I wish I had a better answer for you...

[Pellgunfun]

I have yet to have Chairgun match reality, no matter how accurate my data has been.  I always end up shooting at all of the various distances to get my actual holdover at each distance.  Sorry, I wish I had a better answer for you...

I had that same problem.  Never could I get Chairgun to be spot on.  It's as if there is some hidden setting that I can't find.  I find it impossible to get Chairgun to even match up with Ballistic apps like Strelok Pro.  I still have Chairgun installed, but I seldom ever use it.  I just can't trust it.

[7weight]

I've worked with Chairgun and Strelok concurrently, and they're both generating essentially the same range cards. I shot three distances today and they were close enough that I was surprised. One thing I keep reading about people having issues with Chairgun is when the scope height is not recorded properly.

After shooting again tomorrow, I should have a better idea of real-world results vs. what the computer spits out.

[Pellgunfun]

Not intending to hijack the thread or anything like that but recently Chairgun has been very annoying for me.

It's not saving the data.  I go in and setup my stuff.  Put in all my stuff and save it.  Then I exit and it asked me about overwriting the pellet DB.  It doesn't matter if I say yes or no when it exits and I restart the app all my data is gone and only the original data is there.  Arrgghhhh...>!!!....... 

Back to the topic a bit, I don't use range cards anymore.  I just have the app tell me what the dope is and I dial it in or just use the mil-dots.  Easy-peasy... 

[7weight]

I found something interesting today in both Chairgun and Strelok, I changed the scope power from 2.5x to 5x to 10x to 15x, and generated range cards for each. The reticle views' distances/mils changed, but the range cards remained the exact same  for all 4 powers. I must be doing something wrong, but it was the same for both apps. The scope is second plane, so shouldn't it change?

[Scotchmo]

I found something interesting today in both Chairgun and Strelok, I changed the scope power from 2.5x to 5x to 10x to 15x, and generated range cards for each. The reticle views' distances/mils changed, but the range cards remained the exact same  for all 4 powers. I must be doing something wrong, but it was the same for both apps. The scope is second plane, so shouldn't it change?

What format is your range card? Range card can be in POI/Clicks/Moa/mils/Mil-Dots.

When adjusting the magnification on an SFP scope, only the Mil-Dots change for your range card. If your using any of the other forms (POI/Clicks/Moa/mils), changing magnification makes no difference.

[7weight]

that's what i thought. Check this out.

[Scotchmo]

that's what i thought. Check this out.

Is that Strelok? I’m not familiar with it. If you are set for SFP, the dots columns are wrong for all but the 10x column.

Show me your ChairGun data. I am familiar with ChairGun and it does show the correct dot values with respect to magnification.

[7weight]

It was Chairgun. I'll check with Strelok see what I messed up there.

Not 100% sure what changed, but the Mil-dots finally corrected. The only change I made was to choose a different reticle that closer represented the reticle being used (not a Hawke scope).

[7weight]

Correct me if I'm wrong, as I'm green in these things. Strelok states that MRAD is the same as Mil-dot. Chairgun shows different values for both MRADs and Mils in their tables. At 100 yards, Chairgun shows -5.4 MRAD and -3.6 Mils.

[edit]
Chairgun now shows the same values for both mrad and mils at 10x.

[Scotchmo]

Correct me if I'm wrong, as I'm green in these things. Strelok states that MRAD is the same as Mil-dot. Chairgun shows different values for both MRADs and Mils in their tables. At 100 yards, Chairgun shows -5.4 MRAD and -3.6 Mils.

[edit]
Chairgun now shows the same values for both mrad and mils at 10x.

I'm not familiar with Strelok, but regardless of the program -

Assuming correctly made scopes:

For SFP reticles, MRAD reads same as Mil-dot only when magnification is set to 10x (for standard mil-dots).

For FFP reticles, MRAD is the same angle as mil-dots at all magnifications.

"...Chairgun shows -5.4 MRAD and -3.6 Mils. " That's the correct angular ratio for a SFP reticle at 15x.

Do you mean -5.4 Mil-dots and -3.6 mils?

mils, MRAD, and milliradian all refer to the angular measurement (1/1000 of a radian).

dots or Mil-dots refer to the stadia marks or dots along the reticle axis. Mil-dots are a very specific size dot which is only a milliradian angle when viewed at 10x. With a SFP Mil-dot reticle, you will need to adjust your math for the varying angle, but your reticle will always have the correct ergonomic size. With a FFP Mil-dot reticle, it will be the correct ergonomic size at 10x only, but the angle (milliradiians) will stay constant regardless of magnification.

Whether SFP or FFP reticle, it can only be "true mil dot" when used at 10x.

[JungleShooter]

+1 to what Scott wrote.

The MIL terms all refer to the same concept – an angular measurement, just like MOA.
I have found the following MIL terms in different places and they all mean the same:
mil = mrad = mr = milliradian = milrad = MRad = MRAD = mil dots  [MRad can also mean "group mean radius"]

What probably happens in ChairGun is that the programm tries to distinguish (by use of a different term) how many dots or hashmarks on your scope reticle you need to hold over (or hold under). These dots/ hashmarks are either "mil dots" in case of a metric reticle, or they are "moa dots" in case of a reticle with imperial units.

And those dots/ hashmarks in the reticle do change with the magnification if you have a scope with a second focal plane reticle (SFP, to be distinguished from a FFP = first focal plane reticle [usually more expensive]).


To get this right the shooter needs to know if the scope in use is SFP or FFP.
And s/he needs to select a reticle from the app/ program that matches this (SFP or FFP).
In the reticle view in the app this will display correctly, if the reticle chosen in the app matches the reticle on the actual scope.
In the table view the ballistic data of how many mil dots hold-over should be used is probably only shown for the SPF scope at its calibration setting – and like Scott said, most SFP are calibrated at 10x magnification. At any other magnification setting this value in the ballistics table is useless for a SFP.



As Scott explained, every SFP scope has one magnification setting that the reticle dots/ hashmarks match up with the correct angular measurement (just like an FFP scope where this is true at any magnification).
The most common is 10x, but there are others, so check your manual:
Examples of SPF scopes where the reticle is not calibrated at 10x mangification.     
• Athlon Midas BTR 2.5-15x50
• Athlon Midas BTR 4.5-27x50
SFP, both calibrated at 15x

• Athlon Midas BTR 1-6x24
SFP, calibrated at 6x

Source: https://1410dd2bdd37e05ebf19-a2305060cc55ab8db83b1ef4b8835a6b.ssl.cf5.rackcdn.com/iFDRL6bAGtk0P9OjfpmL1A


• Aztec Emerald 3-18x50 
SFP, calibrated at 9x and at 18x
Source:  https://www.xabla.co.uk/aztec-emerald-3-18


Happy shooting!   

Matthias

[Scotchmo]

+1 to what Scott wrote.

The MIL terms all refer to the same concept – an angular measurement, just like MOA.
I have found the following MIL terms in different places and they all mean the same:
mil = mrad = mr = milliradian = milrad = MRad = MRAD = mil dots  [MRad can also mean "group mean radius"]

What probably happens in ChairGun is that the programm tries to distinguish (by use of a different term) how many dots or hashmarks on your scope reticle you need to hold over (or hold under). These dots/ hashmarks are either "mil dots" in case of a metric reticle, or they are "moa dots" in case of a reticle with imperial units.

And those dots/ hashmarks in the reticle do change with the magnification if you have a scope with a second focal plane reticle (SFP, to be distinguished from a FFP = first focal plane reticle [usually more expensive]).


To get this right the shooter needs to know if the scope in use is SFP or FFP.
And s/he needs to select a reticle from the app/ program that matches this (SFP or FFP).
In the reticle view in the app this will display correctly, if the reticle chosen in the app matches the reticle on the actual scope.
In the table view the ballistic data of how many mil dots hold-over should be used is probably only shown for the SPF scope at its calibration setting – and like Scott said, most SFP are calibrated at 10x magnification. At any other magnification setting this value in the ballistics table is useless for a SFP.



As Scott explained, every SFP scope has one magnification setting that the reticle dots/ hashmarks match up with the correct angular measurement (just like an FFP scope where this is true at any magnification).
The most common is 10x, but there are others, so check your manual:
Examples of SPF scopes where the reticle is not calibrated at 10x mangification.     
• Athlon Midas BTR 2.5-15x50
• Athlon Midas BTR 4.5-27x50
SFP, both calibrated at 15x

• Athlon Midas BTR 1-6x24
SFP, calibrated at 6x

Source: https://1410dd2bdd37e05ebf19-a2305060cc55ab8db83b1ef4b8835a6b.ssl.cf5.rackcdn.com/iFDRL6bAGtk0P9OjfpmL1A


• Aztec Emerald 3-18x50 
SFP, calibrated at 9x and at 18x
Source:  https://www.xabla.co.uk/aztec-emerald-3-18


Happy shooting!   

Matthias

You obviously know the difference between a milliradian and a mil-dot. One is a specific angle, the other is a picture of dots that subtend an angle.

The following is for others that may not know the subtle differences as applied to both SFP and FFP scopes.

"...
I have found the following MIL terms in different places and they all mean the same:
mil = mrad = mr = milliradian = milrad = MRad = MRAD = mil dots  [MRad can also mean "group mean radius"]
..."

I think that's where some confusion takes place. Most of those terms are correctly used to refer to a milliradian angle, except for mil-dot. A "mil-dot" is a specific reticle design that will subtend a milliradian when at 10x magnification.

"...
And those dots/ hashmarks in the reticle do change with the magnification if you have a scope with a second focal plane reticle (SFP, to be distinguished from a FFP = first focal plane reticle [usually more expensive]).
..."

The "change" for the SFP scope is the angle between dots/hashmarks. The dots/hashmarks also change with magnification if you have a scope with a first focal plane. Except it's the ergonomic size (visual representation) that changes.

"...
Examples of SPF scopes where the reticle is not calibrated at 10x mangification.
• Athlon Midas BTR 2.5-15x50
• Athlon Midas BTR 4.5-27x50
..."

Technically, those are various MRAD reticles, not really "mil-dot" reticles.

This is the specific design for mil-dots when used at 10x:


This is what a standard (5mil/quadrant) mil-dot reticle looks like:


This is an extended (9 dot, 10mil/quadrant) mil-dot reticle:


The following are both examples of mrad reticles (not technically"mil-dot" reticles):

[JungleShooter]

Every day on GTA is another opportunity to learn something new.
Thanks, Scott, yes you're right, technically I shouldn't say mil dot if I mean an angular measure, it's a reticle marking, and it's really only for ● , not for this:  │╵∣╵│╵∣╵│╵∣╵│╵∣╵│
I sure prefer the latter....