Could someone please help a paper puncher wrap his brain around FFP/SFP in real life?

[E_T_G]

Hi, All.
I have read until my eyes hurt and just can't get this to click in my head. I have shot paper for over 60 years and I know how to work up a load and get the best groups I can. Hasn't mattered much to me if it was FFP or SFP shooting at a stationary target. What I have little experience with is setting up for a first shot in the field. I've shot my share of ground hogs without any issues, but at 200 yds or less with a 25-06 it would take a gail force wind to have much of an effect on the trajectory. I am going to put a scope on a new-to-me SSG-69 PI. Doing some long range hunting is on my bucket list. If someone could walk me through setting up for that first shot with a FFP and a SFP I would really appreciate it.

To set the scenario lets say the range finder says the target is at 750 yds. The little Kestrel says I have a quartering 9mph headwind from the right and all the other atmospheric data it gives. The target is say 200' lower than me with a clear shot. The rifle will be zeroed at 200 yds. Cartridge is a 308 with 175 SMK at around 2700 fps. How would you set up for the shot with a FFP and then with a SFP. The scope will either be a NX8 4-32x50 or a NXS 8-32x56. I know I could just punch the numbers into a balistics calculator but I really would like to understand it. Your help with tyrying to get through my thick scull is greatly appreciated.

 

[BuildingConceptsllc]

You just need to understand the difference in FFP and SFP . The rest isn't related to that and is the same for whatever distance, elevation, atmospherocs, and wind.

I'd recommend going to YouTube and watching an explanation. The effect on the retical is the issue.

 

[Partsunavailable]

Hi, All.
I have read until my eyes hurt and just can't get this to click in my head. I have shot paper for over 60 years and I know how to work up a load and get the best groups I can. Hasn't mattered much to me if it was FFP or SFP shooting at a stationary target. What I have little experience with is setting up for a first shot in the field. I've shot my share of ground hogs without any issues, but at 200 yds or less with a 25-06 it would take a gail force wind to have much of an effect on the trajectory. I am going to put a scope on a new-to-me SSG-69 PI. Doing some long range hunting is on my bucket list. If someone could walk me through setting up for that first shot with a FFP and a SFP I would really appreciate it.

To set the scenario lets say the range finder says the target is at 750 yds. The little Kestrel says I have a quartering 9mph headwind from the right and all the other atmospheric data it gives. The target is say 200' lower than me with a clear shot. The rifle will be zeroed at 200 yds. Cartridge is a 308 with 175 SMK at around 2700 fps. How would you set up for the shot with a FFP and then with a SFP. The scope will either be a NX8 4-32x50 or a NXS 8-32x56. I know I could just punch the numbers into a balistics calculator but I really would like to understand it. Your help with tyrying to get through my thick scull is greatly appreciated.

It doesn't matter for the first shot. It's the second one that it helps. With the sfp scope you will have to adjust to the magnification that makes the reticle work. Usually that is max power. On the ffp scope, you can use whatever magnification suits you. For that shot, I like about 15x. After that step the process is the same.

Dial your dope, mine is going to be about 21 moa. Elevation, minus a couple because you zeroed at 200 instead of 100, and maybe 2 minutes wind. Take your first shot. Spot your miss. Measure how far you missed with your reticle. Say, you missed two lines low. Now dial up 2 more moa. Fire and measure again.

With the sfp scope, the subtensions in the retical aren't accurate if not set to max power, so you can't measure and dial.

 

[264pr]

Simply put

FFP: Reticle size changes as magnification changes BUT the mil/moa hashes in the reticle remain consistent regardless of magnification.

In other words whether you are at 5x or 25x magnification the value of 1 mil/moa at whatever distance is 1 mil/moa

SFP: reticle size doesnt change with magnification BUT unlike a FFP scope, the value of a hash on the reticle changes with a change in magnification

In other words, 1mil/moa at 4x for 100 yards is a different value than 1 mil/moa hash at 25x and every magnification in between

FFP is far easier to live with....you only need to know/calculate dope once and ts the same across all magnification.....cant tell you how many times I've seen people miss shots with SFP scopes because the values change with magnification

 

[whatsupdoc]

If you are using the scope turrets to dial elevation and windage corrections then there is zero difference. You would plug in the distance
the shooting angle and the wind speed then the kestrel would provide a solution based on the information you entered.
You would then make the changes to the turrets and you are good.

If you are holding over or using the reticle (built in ruler) to measure, a FFP scope's reticle provides an accurate angular measurement regardless of the scopes magnification setting. When using SFP scope to hold over or measure, in order for the reticle "ruler" to be accurate the scopes magnification has to be set to a particular value.

So a simple way to think of it is on a FFP scope the "ruler" is laying on the actual target and when you zoom in the ruler and target
are magnified together. On a SFP scope the ruler is in front of your eye behind the scope and when you zoom in the image in the scope gets larger but the ruler size stays the same.

No reason to zero at 200 zero at 100 and use the turrets.

 

[Rio Precision Gunworks]

Just to clarify, the SFP optic will be “correct” at a set magnification. As in, 1 mil or 1 moa is the same as the 1 mil or 1 moa hash or dot in reticle.

You can still use the SFP in a similar fashion to FFP when not on that magnification, but the values will be different.

For example, if the optic is calibrated at 20x and you have it on 10x, measurements will be halved. Now 1 mil or 1 moa will be the .5 mil or .5 moa mark.

You can do the same thing with both, but SFP is a lot more work and learning.

There’s also the issue of having the SFP at the exact magnification. 20x on the mag ring may be slightly off from actual 20x. So, it can many times be an imperfect system.

 

[Rio Precision Gunworks]

You can use this simple formula to see which hash is what at different magnification:

(Value in Reticle) x (Subtended Power) / (Current Power) = (Value in Reticle at Current Power)

Example; For a 6-18x50 scope that is Subtended at 18x using a 1 Mil hold at 6 power:

1 Mil x 18/6 = 3 Mil

Example; For a 6-24x56 scope that is Subtended at 12x using a 1 Mil hold at 24 power:

1 x 12/24 = 0.5 Mil

 

[E_T_G]

Thanks for your replies. I know the difference between the reticles. I have a NSX, Horus Vision, and a FFP viper PST. Personally target shooting I prefer the FFP. But I didn‘t know if there was an advantage for one when actually in the field shooting at somerhing that can run away. Doing math in my head isn’t as fast as it use to be and my eyes are not far behind. If I‘m shooting at something using a mag low enough to not be able to read the reticle I’d probably just use it like a red dot anyway.
Old Salt, the reason I was going to zero at 200 is that I put a 20 moa rail on it and I didn‘t want the zero to be near the bottom of travel. I might reconsider once I mount the scope and check the travel.

 

[Rio Precision Gunworks]

Thanks for your replies. I know the difference between the reticles. I have a NSX, Horus Vision, and a FFP viper PST. Personally target shooting I prefer the FFP. But I didn‘t know if there was an advantage for one when actually in the field shooting at somerhing that can run away. Doing math in my head isn’t as fast as it use to be and my eyes are not far behind. If I‘m shooting at something using a mag low enough to not be able to read the reticle I’d probably just use it like a red dot anyway.
Old Salt, the reason I was going to zero at 200 is that I put a 20 moa rail on it and I didn‘t want the zero to be near the bottom of travel. I might reconsider once I mount the scope and check the travel.

If it’s a quality optic, you don’t have to worry too much about being at one end of travel.

The only “downside” of FFP is for those who don’t feel they can see/use the reticle on low power.

And technically an SFP optic is more durable historically, though that has basically become a non issue as well.

 

[Holliday]

First focal plane simply guarantees that I won’t need to worry about my magnification setting, to call misses or wind using the reticle.

 

[HenryRed]

Go check out a PRS match. Majority will be shooting first focal plane. Try a match and you might find how much fun it is to turn dial on the clock. Will also help with long range targets. You will also find some great people to learn from. Reach out to the match director for information.

 

[E_T_G]

Thanks everyone. Ordered the NS8 4-32x50 FFP. Now just sit back and wait.
ETG

 

[Milf Dots]

Good info for a newb to precision rifle like me.

 

[tobylazur]

So I have a related question: If you are calling shots and using the reticle for holds does it matter if you are using a FFP or SFP if you are calling your own shots and using your own reticle?

i.e.- If I have a SFP reticle that is set to a power that makes the measurement .66 MIL instead of a full 1 MIL. If I spot my shot as being a full value off (the 1 MIL hashmark) I would think I can just use my reticle as a ruler and hold that indicated one full value mark and re engage? The trouble would be if I'm trying to use the reticle to measure and dial with the turret, or adjust based off a spotter calling shots?

 

[6.5SH]

So I have a related question: If you are calling shots and using the reticle for holds does it matter if you are using a FFP or SFP if you are calling your own shots and using your own reticle?

i.e.- If I have a SFP reticle that is set to a power that makes the measurement .66 MIL instead of a full 1 MIL. If I spot my shot as being a full value off (the 1 MIL hashmark) I would think I can just use my reticle as a ruler and hold that indicated one full value mark and re engage? The trouble would be if I'm trying to use the reticle to measure and dial with the turret, or adjust based off a spotter calling shots?

Your understanding of the differences is correct. Holding where you saw the miss as your new aiming point on the reticle doesn't care if it is 1 mil or .66 or a cubit etc.
If you were trying to dial and do complicated math to convert an angular width to some possibly arbitrary different angular measurement you are going to have a bad time. Most people have a hard enough time going between MIL and MOA in a hurry let alone something non standard.

 

[Trigger Monkey]

the reason I was going to zero at 200 is that I put a 20 moa rail on it and I didn‘t want the zero to be near the bottom of travel.

The difference between a 100 yard zero and 200 yard zero for many centerfire cartridges is equal to or less than 0.5 mil/2 MOA and internally that translates to an erector movement measured in thousandths of an inch.

 

[Tx_Aggie]

Your understanding of the differences is correct. Holding where you saw the miss as your new aiming point on the reticle doesn't care if it is 1 mil or .66 or a cubit etc.
If you were trying to dial and do complicated math to convert an angular width to some possibly arbitrary different angular measurement you are going to have a bad time. Most people have a hard enough time going between MIL and MOA in a hurry let alone something non standard.

Or if shooting multiple targets and trying to transfer a wind hold from a target at one distance to another.

EG: "It looks like I should've used .5 of wind for that 500 yard target, so I'd better go with .7 for the next target at 700 yards."

That would be awfully hard to do on the fly with an SFP reticle set to some arbitrary mag setting where the subtensions are unknown (or require math to be accurate).