The flintlock gun had a lot to do with the end of the samurai period. During the 16th century, Portuguese traders came to Japan to sell the musket guns. These guns quickly became popular all over Japan.

How the flintlock gun works

First, gunpowder is poured into the muzzle, followed by a lead ball. These are rammed in firmly with the ramrod. A small amount of powder is then poured into the pan and pan lid, or frizzen, is closed over it. The hammer is then pulled firmly back and when the trigger is squeezed the flint on the hammer strikes the edge of the frizzen. This creates a big spark, which ignites the priming powder in the pan. A small hole in the barrel allows the burning powder content in the pan to ignite the powder in the barrel, which explodes — firing the lead ball. The flintlock rifle had a range of 75 to 100 metres of distance. 

Since the samurai method of fighting involved close hand-to-hand combat, any weapon that allowed fighting from a distance would make the traditional martial arts of the samurai far less effective. This caused samurai's to slowly evade, because they were no longer needed.