When writing a story, think about the audience. Some people might find it entertaining and informative to read an exceptionally detailed description of what is happening, but most don't. Over-describing an action just to show off knowledge of the topic is generally not beneficial to the readability.
For instance, I could describe reloading a pistol as, "He pressed the magazine release, sending the magazine falling to the ground. He grabbed a replacement and shoved it into the weapon before chambering a round." But really, it is much simpler to say, "He stopped momentarily to reload his pistol." If the reader wishes to know how it's done, they can google it.
There are times, however, when it is beneficial to describe the scene in greater detail. If it will build suspense and keep the reader engrossed in the story, then it might be worth including. For example:
Scenario: Jimmy fires the last shot in his weapon and has to reload. He sees several enemy combatants sneaking up behind his fellow soldiers. He has to reload and shoot at the enemy before his friends are attacked (If I were actually writing this story, I would have tried to make the reader attached to the characters by this point.)
Simple version: Jimmy saw the enemy soldiers approaching as he fired his last shot. He quickly reloaded and opened fire, distracting the enemy.
Detailed version: Jimmy saw the enemy soldier approaching as he fired his last shot. He grabbed another magazine from its pouch and tried to load it into his weapon. His trembling hands wouldn't cooperate and he dropped his ammunition. He looked down for a moment to find it. When he again looked at the enemy, they were bringing their weapons up to aim at his friends. He willed his hands to work, just this once, and managed to load the weapon. He quickly raised it and opened fire on the enemy, hitting several and drawing their attention from the other soldiers.
The simple version is faster and easier, but I believe that the second one is much more interesting. While it might not build much suspense since it is just a single paragraph, the same effect can be achieved in an entire chapter.