This post about optics comes to us from Brian a guest writer and owner of TheNewrifleman.com, where he details his experiences of becoming a well rounded proficient rifleman and getting the most from his AR15.
As times change optics become more pertinent to the rifleman as offering the quintessential advantage in target identification and allowing fast, accurate shooting. The AR15 community has really come to appreciate red dot sights and with good reason. They are fast and are affordable. I want to discuss some features of magnification that don’t often get discussed or that aren’t well understood. There is more to a magnified optic than just a bit of zoom.
I See You: The Advantages of Magnification
Lets discuss the obvious first. The hardest part of engaging distant targets is that they are hard to see. I strain my eyes when trying to focus on targets at 300, and 400 yards and I am shooting man-sized white steel in perfect conditions. It is still hard to see the white target in perfect conditions. If you want to compete or practice at longer range the advantages of even minimal magnification should be apparent.
How easy will it be to ID a threat in a SHTF scenario when the threat is trying not to be seen?
Lets jump to another point of optics that isn’t always discussed: we don’t often discuss the role optics play in a dark environment.
Magnified optics gather light into a focused beam which then funnels it into the pupil. At night your pupil will open up in diameter to let more light in. Let’s look at the specifications of a 4×32 ACOG: 32mm objective lens and it funnels light into a 8mm exit pupil. In the dark your pupil will dilate to 4 – 9mm wide depending on age. At night the wide “eye” of the scope will funnel light into your pupil with max brightness when your eye is dilated to the dark environment.
So how do we put this feature into a quantifiable data? Well, there are actually calculators available to explore the subject. Below is a chart I put together with the low light performance calculator at www.scopecalc.com
The chart allows us to quantify how much brighter the image will seem when viewed through the lens of a scope. The numbers above each ACOG represent how much brighter the image will seem to be based on a maximum dilated pupil of a 30-year-old male (6.9mm estimate).
As we can see the smallest obj 1.5x ACOG gives a 1.374x increase in perceived light while the 4x model gives a 3.107x increase in perceived light. If we balance this with our use and application of the rifle we can better choose an upgrade based on our needs. My SHTF rifle would benefit from a bit of zoom and perceived brightness at night. My home defense rifle would not need these advantages. It isn’t night vision, but it is an advantage we often neglect to think about.
An interesting side note is that the 1-4x variables, by nature of their design, have a peak brightness that occurs at the higher end of the magnification spectrum. As you adjust the magnification of a variable optic the exit pupil diameter shrinks. At 1x the Nightforce 1-4x NXS has a 16mm exit pupil and a 6mm exit at 4x. A 30-year-old male at max dark sensitivity can only let 6.9mm (est) of that light in through his pupil. The Nightforce and its 24mm objective will most efficiently funnel all the light it has gathered at somewhere around 3.5x.
If you want some basic night adapted advantage without night vision, certain magnified optics can give you the edge you are looking for. It is important to balance the features you want with your desired purpose. With a fixed power vs a variable, you are looking at different design elements that give the 3×35 and 4×32 ACOGs an advantage in low light over the variables.
What other features do magnified optics offer?
Target ID and Ranging
Of particular importance is the ability to identify a target at a distance. Not a concern for a home defense setup, but a big factor in a SHTF setup. Here we combine two pieces of equipment: the optic can be used in a manner like binoculars to look at your environment… depending on magnification. Furthermore ranging a target is possible with a basic understanding of your optics reticule. The versatility of variables in multiple settings might be your ticket for a SHTF rifle depending on your goals.
Open rolling hills with 500-600 yard open swaths of land would dictate the necessity of magnification for assistance in target ID. Dense woodlands with no more than 100 yards of visibility might dictate irons or red dots, no magnification needed. A variable could cover both situations. Any upgrade to your rifle is an investment, so think about the scenarios you are likely to encounter. Quality magnified optics are pricey, but they offer distinct advantages depending on your intended usage.
The Weight of Glass
Another point of consideration is that glass is dense and heavy. Currently red dot’s are getting smaller and smaller while the ever popular variables seem to go the opposite direction. The variables bring with them heavy glass and heavy mounts.
I owned a Vortex optics Viper PST and it was a really great mid range 1-4x variable. My time at the range with it was educational and eye-opening. Crystal clear glass, easy identification of targets, and smacking all the steel my range had from 200 to 500 yards was MUCH easier. I ended up ditching it due to weight.
It was 23.3 ounces with scope and ADM mount…. 1.4 lbs For comparison the Aimpoint CompM4 is 11.8 oz with mount. Your specific platform may get away with extra weight, but I didn’t like the weight of the Vortex plus the mount. My rifle felt like it was going to capsize. For someone who hasn’t purchased any optics yet, really look at the weight of the optic + mount. Right now variables are hot sellers. They are affordable and versatile but consider the overall package. The variable I chose ended up on the EE because I underestimated the weight of my setup.
Hopefully I have discussed a few points that are not always thought of front and center when considering magnification. Red dot’s have plenty of advantages, but we should always be investing in upgrades that will help us accomplish our shooting goals with more efficiency. Hitting the target is the ultimate goal and nothing is cheating if it gives you an advantage. Currently I am looking at ACOGs. The light weight and boost in target ID will better suit my goals with my rifle.