Density Altitude – from your device or local online info
Wind – speed and direction
Most of these things you can get from your manual or online info, but how about muzzle velocity? Well, some commercial ammo gives MV, but only from their test rifle and barrel length. If you are going to be accurate, you MUST have a chronograph that measures your shots from your rifle at your DA. Otherwise, you are just guessing and GIGO comes into play – Garbage In, Garbage Out.
DOPE – Data On Previous Engagement. Once we have entered all of this info, the ballistics program will give its proposed solution:
Right you are, Emily! And that leads into a tiny bit more math and science. The basic answer is, of course, to multiply the 11.15 MOA times 5 = 55.75” of bullet drop (almost 5 feet!) BUT, the real world answer has many more variables:
Are the shooter and the target at the same elevation?
What are the atmospheric conditions?
What is the exact distance to the target?
The first variable is pretty straightforward. If both are at the same elevation, it’s a non-issue. However, if one is higher or lower, you have just introduced some geometry into the equation. Since most of your shooting will be level, we’ll look at this later.
The third variable is also straightforward. Emily informed us that the distance was 500 yards, but what was it exactly? If it was 496 or 507 yards, that actually makes a difference. Luckily, the 21st century has laser range finders. But maybe you don’t have one? There’s another way. But also later.
It’s the second question that is most important. What is going on in the air that the bullet must travel through? What is the temperature, the air pressure, the humidity, the elevation? If the air is thick and cold, it will slow the bullet down; likewise, if is thin and hot, the bullet will go faster.
Luckily, people much smarter than you and me have combined all these factors into one variable – Density Altitude, or DA. This number provides us with one number to enter into our firing solution. The best thing about DA is that you can be anywhere in the world and at any temperature, etc. and if the DA is the same, your bullet will react exactly the same. By far, this is the most important variable.
Well, this sounds familiar! Yes, adjustable turret scopes tell you how and how much to move your bullet impact on the target. The Windage knob will adjust the bullet right or left. The Elevation knob on top will move it up and down.
Start by firing a group of three or four rounds at the 100 yard target.
Check the group.
I’d say we want to bring the center of that group down three inches and left three inches. So, if 1 click is a quarter of an inch, 4 clicks is an inch and 12 clicks is 3 inches. Dial the elevation down 12 and the windage left 12. Shoot three or four more rounds. Voila!
Not bad. I’d move windage right 3 or 4 clicks and see if the center of the group is dead on. Don’t be afraid to expend some ammo to get it right where you want it. Once zeroed, you need to be able to return to this setting routinely. Scopes have various ways to do this. This zero point is the basis for everything you will do henceforth.
The Left has been slowly discovering the 2d Amendment. The (almost) comical John Brown shooting clubs are being overtaken by literal calls to arms over the ICE enforcement of federal law against illegal invaders. State officers and other politicians are claiming that stand-your-ground laws allow you to shoot masked law officers. They are not only calling for retribution when they get back in power, but also telling people to keep track of their MAGA neighbors.
Do you understand now that this is not rhetorical, not the LARping of purple-haired, nose-ringed NPCs? It is time NOW to be prepared. If you have dallied in getting some defensive training, or have been saying, “I guess I really should have an AR-15 and both me and my family should know how to use them.”, again, the time is NOW! Get your concealed carry training and license if required *spit*. Do not leave the house unarmed. Ever.
This blog has been around for about a year. If you want to see pretty pictures of cats, they are here. If you want to learn the basics (and a bit more) about firearms, that is here, too. Or even if you just think Emily is cute, she’s here, too.
The tinder is bone-dry and packed up against the gasoline. The Left wants to see literal blood in the streets. It is going to happen.
So, victim or defender of the faith? If you don’t choose, the choice will be made for you.
Yep, I understand. But did you see there’s now a German “Maria”? I wonder if you’re also related…
Back to cleaning. Before we get to the BCG, let’s do a little work on the lower. It doesn’t get as dirty as the upper, but still needs attention. Wipe everything down, including the inside of the mag well.
Put a drop of oil (Mobil 1 works fine) on springs and rotating devices like the safety and the mag release, and operate them a few times for smoothness, then wipe away any excess. The hammer face may be dirty and needs a wipe.
Operate the hammer and trigger, BUT make sure to ease the hammer down with your thumb. You don’t want it flying forward.
That’s the buffer tube. It has a long recoil spring behind it. To remove them you would press down on the little pin in front, and rotate the tube to a flat edge, then pull them out. It doesn’t need a lot of attention, but should occasionally be checked for cleanliness and wiped down lightly with lube.
Give the Lower a wipe down and set it aside.
THE BOLT CARRIER GROUP:
The BCG is the heart of the AR. Practice disassembly and assembly!
That’s the firing pin retention pin.
Remove it and slide the firing pin out.
This is the cam pin. In this position the firing pin goes through a hole in it. It moves in that channel as the bolt cycles forward and back.
It must be rotated 90 degrees to be removed.
And now you can remove the bolt.
Congratulations! Now the cleaning begins. Clean the bolt face – you may need a toothbrush or wire brush to get all the spots.
Take the clean end of your pipe cleaner (oh, yeah. They make special ones about a foot long for ARs) and wet it with solvent.
And clean out the firing pin channel. Blow it clean with a compressed air can after.
Imagine that – more schmutz!
Clean your small parts with solvent. Note the friction wear on the cam pin. Any place you see shiny metal on the gun is a place that will require lubrication when reassembled.
Clean the inside and outside of the carrier. Oh, look, more shiny surfaces!
Now, the gas key.
Get in all the interior nooks and crannies.
Don’t forget the charging handle. The groove gets filthy.
When completely clean, you are ready to REASSEMBLE!
Now, this is my personal choice to use a film of grease for bolt lube. I don’t use it on firearms that will be sitting around a long time – it will cake up. Those guns get CLP or Rem Oil. But I do like it for a regularly used gun.
When lubing the bolt, take time to rotate the three gas rings so that none of them line up.
Remember the wear marks?
The bolt can go in with either end of the cam pin hole up, BUT the cam pin will only go in one of them! (Yes, I do recall an incident with an AR 10 where that was not the case . . .).
Insert and rotate 90 degrees.
Pull bolt forward to check operation. There should be some resistance if the gas rings are operating properly.
Slide firing pin back and retain it. When assembled, shake the BCG up and down. The firing pin should stay in, but move back and forth slightly.
Now, retrieve the upper and lower that you so carefully set aside and start with the pivot pin.
The end of the charging handle goes in and then up and into its channel partway. The gas key on the bolt then fits into the bottom of the charging handle, and the entire unit goes forward all the way.
You can now swing the lower up into position. Make sure the bolt is all the way forward for clearance.
Slide the takedown pin in to place.
Function test by locking the bolt back, releasing it, check that the safety works, then squeeze the trigger. Wipe all the surfaces down and head to the range, where you can dirty it up again!
Here are the deets on adjusting your sights for the 25/300 meter zeroing for M 4 and M 16 style ARs. Shamelessly ripped from the internet.
To achieve a 25/300 meter zero for your AR-15, follow these detailed instructions.
Hang the target so that the center cross is at the shooter’s eye level. For best results, shoot from a benchrest.
Set the rear sight to the appropriate position for your rifle model. For M4-style sights, turn the rear sight to the “8/3” position. For M16A2 and M16A3 sights,
turn up one click past “8/3”. For M16A4 sights, turn up two clicks past the “6/3” setting to the “Z” mark.
Hang the target at 25 meters. Fire precise, three-shot groups at the center dot and adjust your sights according to the targets above. This gives you a battle-zeroed rifle out to 300 meters
And this hack will amaze you! Simply aim at the belt buckle of any ‘target’ out to 300 meters. The round will impact there at 25 and 300. In between it will rise up the torso. At 400, aim at the head and gravity will get you a center of mass hit.
When last we visited Emily, she had shown us how to load and make safe her AR 15. Now, she is ready to shoot.
But how do you aim? How do you hit what you are aiming at?
Great questions! First, you aim using sights, that sounds simple. But nooo. There are as many sights as there are AR variants. So, let’s start with the basics – “iron sights”. That really means “not optical” sights. They are mechanical and are made of steel, aluminum or plastic. They can look like this, front and rear:
And you look through them like this:
Simple, right?
Here, you can see Emily aiming off to the right of the target with the early “carrying handle” and fixed front sight of the original M16 and AR 15.
Precisely because they are simple. No batteries, no fragile optics, and they are hard to damage. They are good out to several hundred yards (depending on your eyes). If you are looking at an AR 15 for general self defense, you can sight in iron sights so that they are zeroed at 25 and 300 meters, and the bullet will only rise a few inches in between. That means you can aim at the center of mass of any target within that range and you will ballistically be guaranteed of a hit. That is why you will see most AR platforms with BUS – Back Up Sights – in addition to optics, red dots, thermals, etc. When all else fails, you can fall back to the simple solution.
These are the targets that the US military sets out at 25 meters (just over 27 yards). By shooting at these close up targets, you can make the required adjustments to the front and rear sights to zero the rifle to the center of the target.
Uncle Sam has made it extremely easy for Pvt. Snuffy to follow these directions. Once zeroed, it will hit the center of the target at both 25 and 300 meters. That’s because the bullet trajectory looks like this:
You can see that the first vertical line is at 25 meters where the bullet climbs through the line of sight, continues climbing and then descends through the line of sight at 300 meters.
KatNap Fever! 