Firearms are tools. Albeit, dangerous tools, but only as dangerous as the user allows them to be. Having said that, follow these simple steps and you can ensure a safe and enjoyable experience with your firearms:
1. Treat every firearm as if it is loaded until you physically ensure it is clear.
2. Never point a firearm at anything you are not prepared to kill, damage, or destroy.
3. Keep your finger off of the trigger until your sights are on a target and you are prepared to shoot.
4. Positively identify your target and know what is in front of and behind it.
Link to Army and Air Force Technical Manual for the M4 in PDF format
Step 1: Start With a Cleared Firearm
The first thing you want to do in the function step process is to make sure your firearm is safe and clear. This is a four step process beginning with ensuring the rifle is on safe as demonstrated in this photo. If the rifle will not go to safe, move on to the next step.
Step 2: Next Step in Clearing: Remove the Magazine
Now that we have ensured the rifle is on safe, we should remove the source of ammunition. Depress the magazine release and completely remove any magazine that is inserted in the weapon. Ensure the magazine well is empty.
Step 3: Next Step in Clearing: Inspect the Chamber
Now we must ensure that there is no live ammunition in the chamber. To do this, pull the charging handle (circled in red) to the rear and and lock it in the open position by depressing the bolt catch (circled in blue) while the bolt is all the way to the rear. Once the bolt is locked to the rear, inspect the the chamber area (circled in green). There should be no ammunition present. Lastly, recheck the safety and place it on safe if it would not go on safe before.
Step 4: Start the Function Check: Safety Check
Now that the rifle is clear, we can begin the check of the rifle's functions. The first function we will check is the safety. Depress the bolt catch/bolt release to let the bolt go forward (circled in blue). With the safety selector lever still in the safe position, press the trigger to the rear as the video demonstrates. There should be no audible click heard because the hammer does not fall. If the hammer does fall, the safety function is not working properly.
Step 5: Continue the Function Check: Check the Semi Automatic Function
Now that we have verified the safety is working, we will move on the next function of the rifle to be checked: Semiautomatic. Place the safety selector lever to the semi position, point the rifle in a safe direction, and pull the trigger. An audible click should be heard as the hammer falls. Hold the trigger to the rear and cycle the bolt to the rear one time by pulling the charging handle all the way to the rear and releasing it. Now release the trigger and listen for an audible click as the trigger is reset. If no audible click is heard, the semiautomatic function of the weapon is not working properly. Refer to the video for a demonstration of this function check.
Step 6: Continue the Function Check: Burst or Full Auto
For civilian models, the function check will be complete after the semiautomatic function has been verified as functional. But for military or government M4 models, the burst or full auto function must be checked. To accomplish this, rotate the safety selector lever around to the burst or auto position. Press the trigger fully to the rear and listen for the audible click as the hammer falls. Hold the trigger to the rear and pull the charging handle to the rear and release three times. After the third cycle of the bolt, release the trigger and listen for the audible click as the trigger resets. If either of the audible clicks are not heard, there is a malfunction with the burst or auto functionality of the rifle. Refer to the video for a demonstration for this step.
Step 7: Final Product
The final product is a rifle that you know is functional. Enjoy and be safe!