As has been mentioned by others, there are often many ways to safely and easily to achieve a positive result. I’m talking about the way I’ve been trained, the way I’ve seen many other trained, and what works for me.
The objective here is to load a cartridge into the chamber, and despite who agrees or disagrees on what method, it really isn’t rocket science so until you get to the point you’re in combat or competition and milliseconds count, don't over-think it. You will be potentially doing this from 2 different conditions. The first condition is from a closed bolt (bolt carrier forward). The second potential condition is open bolt (bolt carrier to the rear, and locked back). Some people prefer to always load from an open bolt, so they will manually lock back the bolt prior to loading.
It makes little difference if you decided to load from an open bolt or a closed bolt. The biggest reasons to load from an open bolt are 1. A positive magazine lock is more easily achieved when magazine spring doesn’t encounter resistance when the top cartridge presses against the bottom of the bolt carrier; 2. You reduce the risk of a misfeed from a “soft” release of the bolt handle; 3. When the bolt has been locked back automatically from an empty magazine 4. It’s easier to inspect the chamber. When reloading, you will almost always load from an open bolt since and empty magazine will activate the bolt catch. Occasionally the bolt carrier will not lock back, in which case you will reload from a closed bolt unless you decide to manually open the bolt prior to reloading. There is no right or wrong if you load from open or closed bolt but I, like many, prefer to load from an open bolt. For me this is primarily because it makes visual and manual inspection of the chamber much easier. To safely inspect the chamber prior to loading you need to cycle the charging handle anyway, and with less than a second you can manually lock the bolt back which will allow you to manually inspect the chamber with less worry of closing the bolt on your finger. This in turn will give you some of the other aforementioned benefits of loading from an open bolt.
To load from a closed bolt:
0. Verify your firearm is pointed in a safe direction, your strong hand (your right hand if shooting right handed) is on the pistol grip, and your finger is stabilized outside of the trigger guard
1. With the magazine removed, fully pull back the charging handle and slightly roll the firearm slightly towards your support side so you can inspect the chamber to ensure it is unloaded (this is when an open bolt fan would manually lock the bolt carrier back, if you want to load from a closed bolt you will release the charging handle to close the bolt)
2. While maintaining your grip, use the thumb of your strong hand to flip the selector to “safe”
3. Leave your strong hand on the pistol grip to hold the firearm and tuck the butt under your right armpit to stabilize it
4. Use your support hand (if you’re shooting right handed this will be your left hand) to retrieve and insert the magazine.
5. Once inserted you use the palm of your support hand to tap upward on the magazine to ensure a positive lock into the magazine catch (loading a magazine into a closed bolt will often require a little of extra force to overcome the magazine spring pressure to fully lock into the catch)
6. Use the support hand to tug on the magazine as if removing the magazine to verify it is locked in
7. Use your support hand to pull back the charging handle all the way and then release to load the first round into the chamber
8. Your firearm is now loaded
To load from an open bolt:
0. Verify your firearm is pointed in a safe direction, your strong hand (your right hand if shooting right handed) is on the pistol grip, your finger is stabilized outside of the trigger guard
1. While maintaining your grip, use the thumb of your strong hand to flip the selector to “safe”
2. Manually and visually inspect the chamber to ensure it is unloaded
3. Leave your strong hand on the pistol grip to hold the firearm and tuck the butt under your right armpit to stabilize it
4. Use your support hand (if you’re shooting right handed this will be your left hand) to retrieve and insert the magazine.
5. Use the support hand to tug on the magazine as if removing the magazine to verify it is locked in
6. Use the palm or thumb of your support hand to press the bolt release to release the bolt carrier and load the first round into the chamber
8. Your firearm is now loaded
There are all sorts of tactical operations you can do in this process to verify a cartridge has been loaded, maintain eyes down range, etc. but these are the basics.
What should my process be from when I am getting the gun ready to firing the gun? Should I not be using the charging handle at all? What's confusing to me is a lot of people don't seem to agree on this.