As I understand a "mil" measures 3.6" at 100 yds, 7.2" at 200, and so on out to 36" at 1000yds. How does the magnification of my scope affect these measurements? I mean, don't they have to be different at 1x, 4x and 10x? Help!!!!!!
Rifle Scopes Mil-Dot Compensation
- Thread starter jbarlow22-250
- Start date
Re: Mil-Dot Compensation
Use the search function in my sig. Type in FFP and SFP...you have a lot of reading in front of you!
The answer to your question depends on what type of scope you have...assuming it is a SFP, yes, the subtentions will only be correct at on mag setting.
Use the search function in my sig. Type in FFP and SFP...you have a lot of reading in front of you!
The answer to your question depends on what type of scope you have...assuming it is a SFP, yes, the subtentions will only be correct at on mag setting.
Re: Mil-Dot Compensation
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: CleanMoostang</div><div class="ubbcode-body">What are you shooting? Rifle/Ammo/shooting location, etc. </div></div>
How does that affect his reticle subtensions?
I highly recommend reading the "optics selection" thread at the top of the forum. It will answer many of your questions.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: CleanMoostang</div><div class="ubbcode-body">What are you shooting? Rifle/Ammo/shooting location, etc. </div></div>
How does that affect his reticle subtensions?
I highly recommend reading the "optics selection" thread at the top of the forum. It will answer many of your questions.
Re: Mil-Dot Compensation
So the simple answer is I need to determine at which magnification my particular scope holds true for the measurements of a "mil"? Or buy a new scope.
So the simple answer is I need to determine at which magnification my particular scope holds true for the measurements of a "mil"? Or buy a new scope.
Re: Mil-Dot Compensation
look up the specs and see if the reticle is in the first of second focal plane.
look up the specs and see if the reticle is in the first of second focal plane.
Re: Mil-Dot Compensation
You can tell if it is FFP by seeing if the reticle changes size with magnification. (No manual needed). If it's SFP, then you'll need to consult the manual to find out what the ranging power is.
Ranging with an SPF scope on a power other than its ranging power is possible, but requires an extra calculation. For example, an SFP scope with 2.5-10X magnification might have 10X as its ranging power. If you ranged @ 5X you'd end up dividing the results by the ranging power divided by the current power, i.e. I'd need to remember to divide by 10/5 or 2. For 2.5X it would be 4.
You can tell if it is FFP by seeing if the reticle changes size with magnification. (No manual needed). If it's SFP, then you'll need to consult the manual to find out what the ranging power is.
Ranging with an SPF scope on a power other than its ranging power is possible, but requires an extra calculation. For example, an SFP scope with 2.5-10X magnification might have 10X as its ranging power. If you ranged @ 5X you'd end up dividing the results by the ranging power divided by the current power, i.e. I'd need to remember to divide by 10/5 or 2. For 2.5X it would be 4.
Re: Mil-Dot Compensation
You need to verify the scope, whatever system or reticle you have or use. It has been my experience that stamped and painted numbers sometimes lie...
Spend the time to verify the adjustments, and the reticle, and if you are ranging on a SFP reticle, don't believe the ring. Mark it yourself after verifying the reticle at distance. Time well spent with a sharpie....
You need to verify the scope, whatever system or reticle you have or use. It has been my experience that stamped and painted numbers sometimes lie...
Spend the time to verify the adjustments, and the reticle, and if you are ranging on a SFP reticle, don't believe the ring. Mark it yourself after verifying the reticle at distance. Time well spent with a sharpie....
Re: Mil-Dot Compensation
He was talking about the drop and inches of a bullets distance at 100 yards, 200, 1000, etc. Compare a .22 and a .308s trajectory.
It would help to know a little more info on his equipment, wouldnt you agree.
He was talking about the drop and inches of a bullets distance at 100 yards, 200, 1000, etc. Compare a .22 and a .308s trajectory.
It would help to know a little more info on his equipment, wouldnt you agree.
Re: Mil-Dot Compensation
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: CleanMoostang</div><div class="ubbcode-body">He was talking about the drop and inches of a bullets distance at 100 yards, 200, 1000, etc. Compare a .22 and a .308s trajectory.
It would help to know a little more info on his equipment, wouldnt you agree. </div></div>
No where in this entire thread did he ask about bullet drop.
He asked if the subtensions of the mil-dots were different at different magnification settings.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: CleanMoostang</div><div class="ubbcode-body">He was talking about the drop and inches of a bullets distance at 100 yards, 200, 1000, etc. Compare a .22 and a .308s trajectory.
It would help to know a little more info on his equipment, wouldnt you agree. </div></div>
No where in this entire thread did he ask about bullet drop.
He asked if the subtensions of the mil-dots were different at different magnification settings.
Re: Mil-Dot Compensation
+1 for Gugubica. Read up so you know the difference between first and second focal plane (FFP vs. SFP). You probably have a second focal plane scope and so yes, things will change with magnification. You can figure it out yourself or call the scope manufacture and ask. Generally it is either 1/2 of full power or full power- at least that has been my experience.
Read a little and all this will become clear. Lot cheaper than buying a new scope.
Good Luck,
Paul
+1 for Gugubica. Read up so you know the difference between first and second focal plane (FFP vs. SFP). You probably have a second focal plane scope and so yes, things will change with magnification. You can figure it out yourself or call the scope manufacture and ask. Generally it is either 1/2 of full power or full power- at least that has been my experience.
Read a little and all this will become clear. Lot cheaper than buying a new scope.
Good Luck,
Paul
Re: Mil-Dot Compensation
Azimutha is correct in theory, but over complicated in practice. No need to change the math.
If your scope subtends correctly at 10x (dot to dot equals one mil), just double the angle at half power...at 5x, dot to dot equals two mils.
This way,you don't have to adjust formulas or only need one cheat sheet.
And yes, FFP does make life easier in this regard, you don't have to be as cognizant of power setting, but it is not a necessity.
Either way, you need to map your reticle (does npt matter what scope).
Azimutha is correct in theory, but over complicated in practice. No need to change the math.
If your scope subtends correctly at 10x (dot to dot equals one mil), just double the angle at half power...at 5x, dot to dot equals two mils.
This way,you don't have to adjust formulas or only need one cheat sheet.
And yes, FFP does make life easier in this regard, you don't have to be as cognizant of power setting, but it is not a necessity.
Either way, you need to map your reticle (does npt matter what scope).
Re: Mil-Dot Compensation
In SFP optics reticle subtension is approximately inversely proportional to magnification (as long as the power ring is cald. correctly). My MD optic is a 6-18x Nikon Buckmasters where the mil is cald for 12x. At 18x it becomes 2.4 IPHY (12/18 x 3.6), and it also measures correctly as calcd. This is the subtension i use for both downrange zeroing and rangefinding with this setup (praire dog rig).
In SFP optics reticle subtension is approximately inversely proportional to magnification (as long as the power ring is cald. correctly). My MD optic is a 6-18x Nikon Buckmasters where the mil is cald for 12x. At 18x it becomes 2.4 IPHY (12/18 x 3.6), and it also measures correctly as calcd. This is the subtension i use for both downrange zeroing and rangefinding with this setup (praire dog rig).
Similar threads
Rifle Scopes
For those about to ... have a March 1-10x24 Shorty!
