Foaming Bore CleanerExpanding foam easily cleans the bore ensures a complete clean. Let expanding foam and time do the hard work in cleaning your firearm.? Foaming Bore Cleaner easily cleans your bore.? Simply spray in the breech end and the foam will expand to fill the bore and ensure complete product coverage.? Let sit until foam breaks down and then remove using an Otis Breech to Muzzle cleaning kit or Ripcord.