PB also makes very good low pressure, BP velcoity loads in .45 Colt. it is very light for it's volume, but is NOT a volume loaded proplellent like Trail-boss is. Trail Boss is only for rifle and pistol rounds, not shotguns that I know of as in heavier loadings in rifles(ei: .45/70's etc, it will develop higher presssure than some guns are meant to handle, with lower velocities than other smokeless propellents. All smokeless propellents MUST be laoded from proper loading manual perscriptions.