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So if you've played call of duty or watched future weapons or whatever then you have probably heard of PDWs. A PDW is a Personal Defense Weapon my take on it is that they are weapons designed to fire the evil armor piercing ammunition. The 3 most popular PDWs I know of are the FN Five seveN, the FN P90, and the H&K MP7.

My big problem with this weapon are potential ballistic problems. These weapons are often praised for having a compact design. That's nice and all, but as a civilian the chances of needing AP ammo isn't very likely. It might be a good military gun, but for civilians I'm not so sure. The ammo is pretty expensive and my take on it is very ineffective for flesh damage.

Let's look at how these bullets are designed. Both FN weapons I listed fire the 5.7x28mm round. That is about .22 caliber. The MP7 fires 4.6x30mm which is about .17 caliber. These are thin rounds with a pointy tip. When these bullets hit a kevlar vest they wiggle through the fibers of kevlar like a sewing needle in a shirt. Once the bullet is through the kevlar it goes through the flesh of the target.

Because these rounds are so light and small I don't suppose they make a very big hole in the target. The old 1911 handgun is very deadly because it uses a big, heavy .45 round. When that bullet hits flesh it drags through the body and does a lot of damage to any nearby organs or blood vessels. A thin, light bullet makes a smaller hole and doesn't have as much drag when sliding through flesh.

The next problem I bring up is rigid armor. Many kevlar armors have pockets for ceramic plates to better stop bullets. These plates can stop 7.62mm bullets from a decent distance. A 4.6mm bullet is carrying considerably less energy and I would assume would be even easier for the plate to stop unless those tips are hardened for extra penetration.

The nato 5.56mm round is a fast and accurate rifle round, but it is light. One of Newtons laws of motion is that force = mass x acceleration. That means the weight of the bullet multiplied by the speed determines the force on impact. A lighter bullet has to travel much faster to equal the same force as a heavier bullet. PDWs, especially the Five seveN, have short barrels which reduces the velocity thus reducing the force on impact.