I had a remington 870 that i recently tried to convert into a slug gun. First two things i did was order a rifled barrel and a shotgun scope. Ive been trying to get this sucker to shoot but it doesnt want to. Is this specific set up with the 870 just cheap stuff, or am i doing something wrong. I put a little money into thinking i would atleast get a decent group at 100 yrds. anyone know something that i dont?