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CatfishKev

FFP VS 2ND FP, POI change

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Makes sense I guess. I suppose what I've read was more specific to bdc scopes as you guys have mentioned.

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Your zero stays your zero (under the exact same conditions) in a FFP or SFP scope on any magnification.  But change conditions, like elevation, temps, etc. it will shift minutely.  Beyond 100 (or 200 if that is your zero) is where you see a difference in drops from where you usually shoot.  Still pretty close out to 400 or so, but changes in POI will occur as conditions change.  Go from low elevation cold weather to high elevation summer weather, and drops change significantly out past 400, and big changes occur past 600-1000+.

Your clicks stay the same in FFP or SFP scopes on any magnification.  1/4 MOA clicks are 1/4 MOA clicks @ 3x or 24X @ 100 yards.  @ 200 yards, they become 1/2 MOA clicks in both FFP or SFP scopes.  400 yards, they become 1 MOA clicks in both FFP or SFP scopes.  800 yards, yep, 2 MOA clicks, 1000 yards, 2.5MOA clicks, and so on.

Subtension values are what change at different magnifications in a SFP, whereas they remain constant in a FFP scope.  A SFP scope with subtensions are ONLY accurate at max magnification & 100 yards.  So say you have a BDC reticle in a SFP scope.  Usually*, SFP BDC reticles are 0, 1.5MOA, 3.5MOA, 7.5MOA, 11MOA (or similar).  That is @ 24X in a 6-24x50 scope.  But, once you turn down magnification, all bets are off.  You have to go to half max magnification to get back on track.  @ 12X, the same subtensions become 3, 7, 15, 22MOA holds.  When you go to 6X, they become 6, 14, 30, 44MOA subtensions.  But only @ 100 yards.  Start moving out, and those numbers change again, and you better break out a ballistic program and a calculator.  

FFP subtensions remain constant at any magnification.  A 5 MOA mark is a 5 MOA mark @ 6x, 8X, 12.2X, 15.7X, 20.1X, or 24X.  At 100 yards.  At 200, they double in inches. Still 5MOA, but it is now 10".  At 300, they triple to 15" at 400, the quadruple to 20" which is still 5MOA.....@ 1000, they are 10X or 50" but still 5 MOA (yeah, I don't know that term).  But magnification has no effect of subtension values.

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On a second focal plane scope the crosshair zero doesn't change at different power. If you have a bdc or hold over reticle, the hash marks below the crosshair do change value at different powers. 

Most of the BDC reticles are designed to be used on the highest power of the scope. That isn't 100% true though. 

My leupold vx6 with Boone and Crockett reticle has 2 different power settings, and you use the one that more closely matches your cartridges drop characteristics. 

On a first focal plane scope, the mildot or hash marks mean the same thing at all powers. 

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So here is my piece of advice.   Go shoot your gun and adjust the crap out of your scope and see how it shoots for you.   Then you will know.  I've seen scopes that have to be at a specific power for the BDC to work.   I've seen it where it has to be at max power for the BDC to work.  Personally, I will shoot my gun at the distances I might shoot in the field and see how my equipment works for me.   There are tons of critters missed or wounded because guys did a ton of internet research and didn't take the time to go bust primers and see what actually happens in the real world.

I own both the FFP and SFP scopes.  I really like the SFP scopes with the BDC in the reticle for most practical hunting applications.   Not always the best for shooting out past 600 yards but for killing most critters it does really good.      

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On 11/10/2018 at 12:10 PM, lancetkenyon said:

Your clicks stay the same in FFP or SFP scopes on any magnification.  1/4 MOA clicks are 1/4 MOA clicks @ 3x or 24X @ 100 yards.  @ 200 yards, they become 1/2 MOA clicks in both FFP or SFP scopes.  400 yards, they become 1 MOA clicks in both FFP or SFP scopes.  800 yards, yep, 2 MOA clicks, 1000 yards, 2.5MOA clicks, and so on.

Your statement is a little off Lance. 1/4 moa clicks are 1/4 moa clicks no matter what and that never changes. 1 MOA at 400 yds is approx 4”, so the 1/4 MOA click is 1” at 400 yds. Nothing changes to 1/2 moa clicks or moa clicks no matter the distance.  At 1000 yds, 1 click on a 1/4 moa scope is about 2.5 inches, which is still 1/4 moa. 

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On 11/12/2018 at 11:35 AM, AverageJoe said:

Your statement is a little off Lance. 1/4 moa clicks are 1/4 moa clicks no matter what and that never changes. 1 MOA at 400 yds is approx 4”, so the 1/4 MOA click is 1” at 400 yds. Nothing changes to 1/2 moa clicks or moa clicks no matter the distance.  At 1000 yds, 1 click on a 1/4 moa scope is about 2.5 inches, which is still 1/4 moa. 

You are correct.  Your click now adjusts point of impact 2.5" @ 1000 yards.  Should have said 2.5", not 2.5 MOA. 

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