Will a Winchester 1300 Defender shoot Remington Copper Solid Sabot Slugs?

Yes; however, the Remington Coppersolid slug is designed for shotguns with fully rifled barrels. A rifled barrel is not standard on the 1300 Defender but is available as a replacement. The Coppersolid slug can be fired from a 1300 with a standard smooth bore barrel, but long range accuracy will suffer.