霰弹块（Shotgun slug）或称一粒弹、一块弹、独头弹，是给霰弹枪发射的铅制的抛射物（弹头），本身可能有着预先制好的膛线，通常用来猎杀大型猎物。第一种有效的霰弹块是由Wilhelm Brenneke在1898年制出，他的设计到今日仍在使用。

大部份的霰弹块设计用来通过滑膛枪管，这代表它们必须自我稳定才能够通过缩管。后来霰弹枪的枪管也出现了线膛管，霰弹块也设计成用来被它们发射，并透过自旋来达到稳定。由于这些线膛的霰弹枪比传统的滑膛霰弹枪的准度更高，它们通常也安装了如瞄准镜之类的光学设备。很多霰弹块使用了会脱壳的次口径抛射物，使它们的外弹道表现大幅提升。

A modern shotgun slug is a heavy lead, copper-covered lead or other material (like steel or wax) projectile, with or without a plastic tip, that may have what appears to be rifling, but these are special cuts in the slug to let it deform when passing through a tight choke. Slugs are intended for use in a shotgun and often used for hunting large game. The first effective modern shotgun slug was introduced by Wilhelm Brenneke in 1898, and his design remains in use today. Most shotgun slugs are designed to be fired through a choked smoothbore barrel; they must be self-stabilizing in the absence of rifling.