What is fn 5.7 rounds?

FN 5.7 is a cartridge designed by FN Herstal in Belgium in the late 1980s to accompany the P90 personal defense weapon and Five-seveN pistol. The cartridge is also known as the SS190.

The FN 5.7 round is a bottlenecked cartridge, which means that the case narrows between the neck and body, increasing pressure to achieve higher velocity and accuracy. The round is known for its high velocity and flat trajectory and is designed to increase the lethality of smaller caliber firearms.

The FN 5.7 round has a brass casing with a total length of 28.95 mm and a bullet diameter of 5.7mm. It is a centerfire cartridge with a small flash hole in the primer pocket and is loaded with a pointed, polymer-tipped 31-grain bullet made of aluminum, copper, and steel.

The cartridge is designed to have low recoil and to deliver rapid and accurate fire, making it an ideal choice for law enforcement and military operations. It is capable of penetrating body armor and is considered a superior choice for its penetration capabilities.

Overall, the FN 5.7 round is a highly effective and reliable cartridge that has gained popularity with law enforcement and military personnel worldwide.