pile gun

例句：

1. 1. They used to use a pile gun for target practice.
   他们过去使用一个堆叠式枪支进行射击训练。
2. 2. The police found a pile gun in the abandoned house.
   警方在一座废弃的房子里发现了一个堆积式枪支。
3. 3. The military had a pile gun that could fire multiple rounds at once.
   军队拥有一种可以同时发射多轮子弹的堆积式枪支。