The principle of maximum caliber is a fancy way of saying that when you shoot something, you want to use the biggest, most powerful bullet that you can. It's kind of like when you play a game of rock-paper-scissors and you want to use rock because it's the strongest.
Basically, the idea is that if you shoot something with a bigger, more powerful bullet, there will be less chance of something going wrong. The bullet will go faster, hit harder, and do more damage.
Imagine you're shooting at a target. If you use a really small bullet, it might veer off course or not do much damage when it hits the target. But if you use a big, powerful bullet, there's a better chance that it will hit the target and do enough damage to knock it down.
It's important to remember, though, that using the biggest bullet isn't always the best option. Sometimes smaller bullets can be more accurate or easier to handle. But when you're trying to hit something far away or need to take down a big target, it's a good idea to use the maximum caliber bullet you can.