rammer

noun2

1. •
   A device used to ram; a ramrod.

   • Now use your rammer to pack it tightly into the barrel.
2. •
   One who, or that, rams.

   • The loader […] placed the cartridge in the muzzle and shoved it in as far as he could. The rammer rammed it home, the gun captain inserting his priming wire to make sure. — 2014