need help with 870 please
 

what are the best slugs for a remington 870 pump something that shots tight groups but has punch for that bucks benekee black magics 3" did not work thanks

Do you have a rifled barrel? If so, than any saboted slug should work.
You will have to put in the effort to find out what works best for you gun.
If your still using the smooth bore, than the foster type slug and a prayer, as well as practice to find out how your gun shoots this style of slug.

If you're gunning rifled slugs, try the federal tru-balls. They've worked quite well for me.

On the smoothbore 870, the regular Rem 1oz sluggers grouped well out to 75yards for me.
The Truball slugs also were a good choice.