Calculating Theoretical Holds

Grim

Grim

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I've tried to make sense of calculating theoretical dialed elevation with various optics, obviously some have been easier than others, but I have the hardest time with my Sig SSG3000 using a Schmidt & Bender PMII, largely because it's a different unit than what I have the most experience with.

The units are marked as 0.25cm for windage and elevation. Theoretically speaking, the following click value should be true, correct?

100 - 0.25cm
200 - 0.50cm
300 - 0.75cm
400 - 1.00cm
500 - 1.25cm
600 - 1.50cm
700 - 1.75cm

So when I attempt to identify my theoretical elevation my values are significantly off from what my actual verified adjustments have been.

Could someone share their equation for calculating theoretical elevation? Thanks in advance.

I have had success in the past by taking the known drop, as indicated by the manufacturer, and dividing it by the unit of measure (click value at a known distance). That usually places me within a few inches of observed impact.
 
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Me. said:
I’m no long-range guy, so excuse me if I have the terms incorrect....

You mention calculating “holds”, but then you mention “clicks”. If you are dialing in clicks, wouldn’t your “hold” be right on the center of the reticle?

Conversely, if you’re “holding over”, wouldn’t you not be “clicking”?
Click to expand...
Correct. I'll amend the post to be specific.
 
Are the distances you reference in Yards or Meters? I’d assume if the adjustment specifically calls out “cm” that the index is meters.
 
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Just use the JBM Calc tool to generate a trajectory table.
https://www.jbmballistics.com/cgi-bin/jbmtraj_simp-5.1.cgi

You can enter all the relevant data in metric and the output includes a "centimeter per 100m" option. Here's an output example for .308WIN 168gr. You should be able to figure out the number of quarter-centimeter clicks from the table.

upload_2020-4-15_8-13-4.png
 
Tim said:
Are the distances you reference in Yards or Meters? I’d assume if the adjustment specifically calls out “cm” that the index is meters.
Click to expand...
The manual identifies turret configuration as 0,25cm yet there is nothing that identifies the distance at which that is measured. Field of view is stated at 12.6m-3.30m / 100yd, which makes me believe the unit of measure is 0.25cm at that stated distance.
 
Tim said:
Are the distances you reference in Yards or Meters? I’d assume if the adjustment specifically calls out “cm” that the index is meters.
Click to expand...
After performing the calculations using 100m zero, my calculations are significantly closer, like within an inch of observed data.

On a side note; how hard is it to clearly state that the optical adjustments are 0.25cm/100m somewhere in the manual. One would have imagined that would be something clearly stated.
 
nbkky71 said:
Just use the JBM Calc tool to generate a trajectory table.
https://www.jbmballistics.com/cgi-bin/jbmtraj_simp-5.1.cgi

You can enter all the relevant data in metric and the output includes a "centimeter per 100m" option. Here's an output example for .308WIN 168gr. You should be able to figure out the number of quarter-centimeter clicks from the table.

View attachment 204793
Click to expand...
That is actually a big help. Reduces a lot of the calculation by adding the cm/100m option.
 
Tim said:
Are the distances you reference in Yards or Meters? I’d assume if the adjustment specifically calls out “cm” that the index is meters.
Click to expand...

Not true, "cm" is the equivalent of "1/4 inch" It's a marketing person at a company assuming the end user does not know MIL or MOA.
 
@Grim,

Cool,

run the JBM data with that info you just posted and for adjustment do it in .1MIL and then download that to excel.

You are done.

Example:
100 = 0
200 = 0.5
300 = 1.2
400 = 2.3
500 = 3.4

The numbers of ( 0.5, 1.2, 2.3, 3.4 ) are not click value. This is the whole number you dial to. This whole number is the DOPE for that yard line.

IF you want click value, you need to use a scale. Typically click value scale is between the distances (distance A to distance B) As an example.

(distance a) 100 = 0
(distance b) 200 = 0.5

0.5 is the MIL adjustment between 100yds and 200yds

.025 is the value of your "clicker"

take 0.5 / .025 = 20 clicks

This means you have 20 clicks between 100yds and 200yds.

200 yards to 300yds

1.2 -.5 = .7

.7 is the MIL between 200yds and 300yds

.7 / .025 = 28 clicks

You are welcome. LOL
 
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It's a quarter MOA adjustment, per the U.S. data sheet.

ETA: Disregard this post, this was incorrect.
 

Attachments

  • db_12-50x56_pmii_us.pdf
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Matt.Cross said:
It's a quarter MOA adjustment, per the U.S. data sheet.
Click to expand...

You're assuming he bought a US Market product and not a Euro one. If his turrets read ".25cm" it would logically follow that it's indexed for .25Mil/100Meters
 
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Tim said:
You're assuming he bought a US Market product and not a Euro one. If his turrets read ".25cm" it would logically follow that it's indexed for .25Mil/100Meters
Click to expand...

I didn't really assume anything to be honest, I just went to the German website and downloaded the U.S. data sheet for his specific optic. Would the U.K. version of the data sheet correspond to the European version of the optic?

Let me illustrate by a screenshot from the German data sheet:
Screenshot_20200415-122659.png
 
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It is not the MOA variant, this is the 0,25cm variant. It is listed in the page that Tim linked for click values.

John's calculations are the most accurate against my observed data (confirmed on paper). Thanks for all the help! It'll save me a lot of ammo getting data.
 
JBoyette said:
Not true, "cm" is the equivalent of "1/4 inch" It's a marketing person at a company assuming the end user does not know MIL or MOA.
Click to expand...

In what way, exactly, was my statement 'not true'?
 
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Here's a photo of the turrets. You may be able to see it clearly marked here, if not, I'll get another photo when I get home.

93515751_250560459402451_5562236596851310592_o.jpg
 
Using John's method, compared to what my actual observed dialed adjustments, it's coming up incredibly close. My observed data may just be a hair off due to the fine adjustment.

Data below is the position on the scope from zero. As it is a multi-turn scope, you just keep dialing it up and it lets you know which rotation you are in, so it makes it easier to identify which position you are in.

Distance - Theoretical - Observed
100 - 0 - 0
200 - 4.00 - 5.00
300 - 11.50 - 13.00
400 - 21.75 - 23.00
550 - 38.75 - 39.00 (damn that one is incredibly close)

I have since been able to calculate my dialed elevations out to 1000 fairly quickly.
 
Tim said:
In what way, exactly, was my statement 'not true'?
Click to expand...

When you mixed the angler unit of measure with linear

"Are the distances you reference in Yards or Meters? I’d assume if the adjustment specifically calls out “cm” that the index is meters."

Linear unit of measure has nothing to do with this conversation.
 
Grim said:
Using John's method, compared to what my actual observed dialed adjustments, it's coming up incredibly close. My observed data may just be a hair off due to the fine adjustment.

Data below is the position on the scope from zero. As it is a multi-turn scope, you just keep dialing it up and it lets you know which rotation you are in, so it makes it easier to identify which position you are in.

Distance - Theoretical - Observed
100 - 0 - 0
200 - 4.00 - 5.00
300 - 11.50 - 13.00
400 - 21.75 - 23.00
550 - 38.75 - 39.00 (damn that one is incredibly close)

I have since been able to calculate my dialed elevations out to 1000 fairly quickly.
Click to expand...

BTW,

Thats off the cuff.

I have been shooting .308win since 1998. LOL
 
Grim said:
Here's a photo of the turrets. You may be able to see it clearly marked here, if not, I'll get another photo when I get home.

93515751_250560459402451_5562236596851310592_o.jpg
Click to expand...
JBoyette said:
BTW,

Thats off the cuff.

I have been shooting .308win since 1998. LOL
Click to expand...

I would raise hell with S&B the turret is improperly marked. Its 0.025MIL not 0.25CM That is at the heart of this whole post.
 
JBoyette said:
When you mixed the angler unit of measure with linear

"Are the distances you reference in Yards or Meters? I’d assume if the adjustment specifically calls out “cm” that the index is meters."

Linear unit of measure has nothing to do with this conversation.
Click to expand...

*I* didn't mix the units, the manufacturer did. The manufacturer chose to indicate ".25cm" rather than mil. So, it is then logical to describe the relation between the MANUFACTURER saying ".25CM" to the 100 Meter index. Telling the end user (shooter) that what I said is wrong is a disservice and is wrong in its own right.

I'd put my long range skills up against anyone here; I know mil/moa as well as anyone. I wasn't wrong or 'untrue' as you say in any way. You seem to know what you're doing, you should try being less of an ass about it.
 
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I appreciate all the help. It was a long, and expensive process to get my confirmed data to 550 without what has been shared here, as I would shoot, make adjustments, see things haven't moved much, then adjust more. Makes for a lot of rounds down range at match ammo prices.

At least the next group of distances 550-1000 should be a bit quicker to identify and fine tune.
 
Tim said:
*I* didn't mix the units, the manufacturer did. The manufacturer chose to indicate ".25cm" rather than mil. So, it is then logical to describe the relation between the MANUFACTURER saying ".25CM" to the 100 Meter index. Telling the end user (shooter) that what I said is wrong is a disservice and is wrong in its own right.

I'd put my long range skills up against anyone here; I know mil/moa as well as anyone. I wasn't wrong or 'untrue' as you say in any way. You seem to know what you're doing, you should try being less of an ass about it.
Click to expand...

Ok,

Go enjoy your day then
 
Grim said:
Here's a photo of the turrets. You may be able to see it clearly marked here, if not, I'll get another photo when I get home.

93515751_250560459402451_5562236596851310592_o.jpg
Click to expand...

After studying your optic @Grim you understand that the elevation and windage whole numbers are in .1 MIL?

So when your elevation knob says 2 thats a .2 and the whole rotation is 3.5 MIL

John
 
Wow, it's pretty convoluted, but the numbers make sense now.

.1 Mils @ 100 meters = 1 centimeters

So every click is .25 centimeters @ 100 meters, or .025 Mils per click. Every 4 clicks is 1/10th Mils as marked on the turret.

Briefly stated, 4 times as many 'clicks' per tenth mil than a standard tenth mil turret.

So where .1 Mils corresponds to .36" at 100 yards, one click in this case is .09" at 100 yards.

100 yd = .09" per click
200 = .18"
300 = .27"
400 = .36"
500 = .45"
600. = .54"
....
1000 = .9" per click

Finally, John was exactly correct about it being a Mil based adjustment. Further reading of S&B's documentation proved that to be the case.
 
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Matt.Cross said:
Wow, it's pretty convoluted, but the numbers make sense now.

.1 Mils @ 100 meters = 1 centimeters

So every click is .25 centimeters @ 100 meters, or .25 Mils per click. Every 4 clicks is 1/10th Mils as marked on the turret.

Briefly stated, 4 times as many 'clicks' per tenth mil than a standard tenth mil turret.

So where .1 Mils corresponds to .36" at 100 yards, one click in this case is .09" at 100 yards.

100 yd = .09" per click
200 = .18"
300 = .27"
400 = .36"
500 = .45"
600. = .54"
....
1000 = .9" per click

Finally, John was exactly correct about it being a Mil based adjustment. Further reading of S&B's documentation proved that to be the case.
Click to expand...

This optic is designed for 1000yds< not >1000yds. It took me a bit to figure it out, but as with most S&B stiff its a marketing nightmare until Derrick Bartlett tells them to change it.

This is why the click value is .025 not .25

Now, if you look at the click value in inches past 1000yds, compared to a .1 MIL it makes perfect sense when sitting ontop a 40MOA based 338LM.

Keep in mind,

MIL is 1/1000 scale

Meter is also 1/1000

this allows the ill informed to make some connection to mil/meter idea that is just not true.

I can do 1/1000 just as easy in "yards" as "meters"
 
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JBoyette said:
Now, if you look at the click value in inches past 1000yds, compared to a .1 MIL it makes perfect sense when sitting ontop a 40MOA based 338LM.
Click to expand...

I agree in terms of elevation adjustment, is windage on the same adjustment system though? 'Cause if it is, that sounds like a nightmare.

It seems this would also have some appeal to F-class shooters looking for high-resolution adjustment.
 
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Matt.Cross said:
I agree in terms of elevation adjustment, is windage on the same adjustment system though? 'Cause if it is, that sounds like a nightmare.
Click to expand...

Yes sir, all day long.

This is why I would teach in 10mph + days to dial the average full value and hold the pickup and let offs.

But if its under 10mph and under 600yds, just hold elevation and wind. Over 600yds dial elevation and hold wind.
 
A few more photos of the optic (Schmidt & Bender PMII 12-50x56).

Elevation turret (multi-turn)

93421082_250695842722246_1172651347414089728_n.jpg


Windage turret

93258628_250695799388917_172357561574490112_n.jpg


Reticle (P4 Fine)

93360798_250695776055586_7062545725057400832_n.jpg
 
I like the optic alot.

It reminds me of when Leopold went from the Ultra to the MK4 and did the M1 turrets in 1/8 inch" but still laser marked 1/4"

The issue with a linear unit of measure for marking on a turret is, it only works for one distance. in both cases the Leopold and this S&B is at 100. this is one more example of the Product Manager not knowing the end use. This same thing also happened on the 10x PMII S&B's. I had two of them back in 1999-2001 for contract training work. (wish I never sold them) I had one that was for Accuracy International AIAW it was .1MIL and the other was for Dallas SWAT it was .1cm. Same damn optic, different marked turrets.
 
JBoyette said:
I like the optic alot.

It reminds me of when Leopold went from the Ultra to the MK4 and did the M1 turrets in 1/8 inch" but still laser marked 1/4"

The issue with a linear unit of measure for marking on a turret is, it only works for one distance. in both cases the Leopold and this S&B is at 100. this is one more example of the Product Manager not knowing the end use. This same thing also happened on the 10x PMII S&B's. I had two of them back in 1999-2001 for contract training work. (wish I never sold them) I had one that was for Accuracy International AIAW it was .1MIL and the other was for Dallas SWAT it was .1cm. Same damn optic, different marked turrets.
Click to expand...
I'm still amazed that their manuals are very lacking. I have done technical writing for a pharmaceutical company, and we obviously are driven by outside agencies to be very detailed in our information, but I was honestly very disappointed by S&B's. Unfortunately, the same goes for Sig Sauer's optics, though I found that they were a bit more intuitive to use.

So far my favorite optic for ease of use has been the NightForce NXS line of optics. While they're not as high quality in glass and tactile feel of turrets over Schmidt & Bender, their optics and manuals are very detailed and generally easy to use (which is why I'm going to add one on my next hunting rig - I purchased a NXS 5.5-22x56).
 
Grim said:
So far my favorite optic for ease of use has been the NightForce NXS line of optics. While they're not as high quality in glass and tactile feel of turrets over Schmidt & Bender, their optics and manuals are very detailed and generally easy to use (which is why I'm going to add one on my next hunting rig - I purchased a NXS 5.5-22x56).
Click to expand...

I recently purchased a NXS 8-32x56 and it is just amazing. You're right that NF documentation is excellent and easy to use.

Does the S&B have the equivalent of NF zero stops?
 
Matt.Cross said:
Does the S&B have the equivalent of NF zero stops?
Click to expand...

Yes, it's integrated into the multi-turn turret. It will only rotate a set distance from the "bottom" which can be adjusted to the new "bottom" whenever it is removed.
 
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