Bore Solvent
A chemical cleaner that dissolves carbon and copper fouling from the bore, applied on patches and brushes between firing strings.
Bore solvent is the liquid cleaner that does the chemical half of barrel maintenance, loosening or dissolving the residue that firing leaves behind. Most products attack carbon, and dedicated copper solvents chemically break down the copper-fouling jacketed bullets smear into the rifling. Some are formulated to do both at once, so the choice often comes down to how heavy and what type of fouling has built up.
The usual routine is to wet a patch or a bore-brush with solvent, let it dwell in the bore so the chemistry has time to work, and then push clean patches through to carry the dissolved residue out. Copper solvents in particular need a few minutes of dwell and should not be left indefinitely, since the stronger ones can etch steel if forgotten. A solvent differs from a combined product like clp, which trades some cleaning aggression for added lubrication and corrosion protection.