Federal introduced the Expanding Full Metal Jacket (EFMJ) a few years back, and those rounds have been fairly well received. Â More recently, the company introduced the Guard Dog line of personal defense ammunition, which uses similar technology.
The design concept is to achieve an expanding bullet without using a traditional hollow point. Â In some pistols, a hollow point bullet design doesn’t reliably feed. Â Even more, people run into the problem of hollow-point ammunition not being legal in some places (like the entire state of New Jersey). Â Another problem with traditional hollow points is that material can plug the hollow point and prevent expansion.