I have used the Copper Solids for only one year. I sighted my gun in and practiced with them to get used to my slug gun. Didn't have a deer come into range this season while using my Remington 870. I think the slower sabots (about 1500 fps or so) work well in barrels with 1 in 34" twist rate andbarrels with 1 in 28" twist rates might prefer the newer/faster slugs (up to 2000 fps). I'm not sure whattwist rate the NEF guns have, but I would check into it and buy accordingly.