So, you have an accurate rifle, you have worked out your handloads or found some factory ammo that cuts one ragged hole at 100 yards and you want to start shooting farther. But you don’t want to buy a new scope. How do you know where to hold for longer distance more accurately than just doing a little “Kentucky hold” ? With a little bit of work you may be able to use the reticle substension data.
For the purpose of this article I am going to stick with standard second focal plane scopes (SFP). With a SFP scope, you need to have them at max power for the following to work right. Additionally, the application will be biased towards hunting as what I am covering would be of interest mainly to hunters not tactical or competition use, though in a pinch it could work for those applications as well.
I am also going to stick with 400 yards as a max range as with even flat shooting catridges that is about the point where the bullet starts it’s dropping faster.
Past 400 you should be looking at scopes with a mildot reticle, or perhaps a BDC reticle though I am not generally a fan. The best option is a “tactical” scope where you can dial in the exact elevation correction needed. Past 400 the wind starts to really have an effect as well.
I am going to make an assumption that you have a decent range finder and we will not be using the reticle for ranging like you can do with a mildot reticle.
One little trick I like to use is if I am hunting an area where I am going to be stationary is to range key landmarks like different trees for example and so if something come out I have a mental map in my head of the area. Additionally, sometimes I will put out corn as bait (legal in Texas) at varying ranges that I know, so, I may put out corn at 250, 300, 350, 400. Yes, I like to cheat, or, maximize my chances for success.
For hunting, I like a flat shooting rifle as 90% of my shots will be within 300 yards and I can run a zero that keeps me + – 2-3″ out to 300 yards. Meaning I don’t have to really worry about it, see game, put crosshair where I want the bullet to hit and squeeze trigger.
What we are going to do is use the reticle’s measurements to enable us to make good accurate hits on target. For game, I consider that about 4″. Yes, the vitals of a deer if you are going for a heart shot are much bigger. But I don’t often take heart shots because I HATE tracking. I want to anchor them on the spot. That means disrupting the CNS or taking out the running gear, neck, high shoulder shot, base of neck, etc.. I also believe in aim small/miss small.
Reticle substension data is basically the specs of the reticle. Typically given at 100 yards, they represent the distances between lines or the size of a dot, etc..
Say your scope has center crosshair and vertical stradia line gets thicker 4″ below the center of the reticle. That means that same space between the center and the start of the thicker section will be 8″ at 200 yards, 12″ at 300 yard, etc.. (we will assume you are running a standard hunting scope with the reticle in the 2nd focal plane where you need to be at max magnification for all of this math to work right) Once you know that data, you can use a ballistics calculator to figure out the trajectory with given zero yardage ranges and find a zero setting, the trajectory of your load and the substension data to make something useful.
If you can’t find the substension data, or want to verify it you can put up a target with 1″ grid lines at 100 yards. I have a board in a tree 100 yards behind my back deck with lines marked on it. As I am always testing scopes out I like the convenience of being able to do this from my back deck.
My main hunting rifle is a Nosler 280 Ackley with the following ballistics info:
- 140g Accubond at 3150 FPS
- 250 yard zero
- +2″ at 100
- -3″ at 300
- – 7″ at 350
- -13 at 400
I have grown to really like a Meopta 3-12×56 RD for hunting. Outstanding glass that competes with the top Euro glass.
The scope has a unique reticle where there is a 1″ dot in the center with a gap to the vertical stradia line that is 2″ below center.
Time to do some math!
So, with a 250 yard zero and knowing that my next 50 yard increment is has the bullet hitting 3″ below the center I can start doing my calculations.
Knowing that the top of the vertical stradia is 2″ below center at 100 yards means it is 4″ at 200, 6″ at 300, 8″ at 400.
I can then figure out my holdover points using the reticle, not the air or guessing..
So, there is a distance of 6″ between the center of the reticle and the top of the stradia, my bullet will impact 3″ below the center crosshairs, or, right in the middle between center of reticle and top of line. Pretty easy to simply bracket/center the reticle with where I want the bullet to go and squeeze trigger.
At worst and assuming a steady rest I will be 1-2″ high or low..
At 350 my bullet hits 7″ low, perfect!
What? Why is that perfect??? Well, if the distance between center and top of stradia is 6″ at 300 and 8″ at 400, well, that means it’s 7″ at 350!
350 yard target? Just put the top of the line in the vitals and pull.
400 shot gets a little trickier but not is still pretty straightforward.
My bullet would impact 13″ below where the center crosshair is aimed.
Given that at 400 yards the distance between the center crosshair and the top of the bottom vertical stradia is 8″, my bullet would hit 5″ below that mark ( 13-8=5)
So, I use the top of the line and know that the bullet will hit 5 low and pull up slightly to compensate. I would hold top of front shoulder at 400 yards on a deer and top of the head of a boar just behind the ear on a side profile shot. Frontal shot is easy as well.
It really is pretty simple if you take the time to work it out..
A GREAT way to practice is to put some clay pidgeons on a berm at varying distances. If you can quickly and consistently bust 3″ clay pidgeons you are good to go!
Here is the data I worked out in MSPAINT. I made a small cheat sheet and take it to the rifle.
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