I find English single barrel breechloaders are often lighter than their double barreled counterparts. 8's weighing 12 to 13lbs for 10 drams and 4's weighing 15 to 17lbs for 12 to 16 drams. I guess if you only bought a single you had to tough out the recoil. Many 4 bore rifles had bore diameters that correspond to 5 or 6 bore but used the 4 bore case.