Im shooting a Remington 870 super mag with a 28" barrel with winchester 3.5" #5 shells and I have a remington superfull choke and Im not getting a reall good pattern out to 40 yds I was wondering if I should go with a #6 shot or go with a new choke tube. I was also wondering what makes a difference with two different choke tubes that have the same constriction. such as a remington super full and the undertaker with a constriction of .665. what will make one better than the other? one more thing is what do you guys suggest for a choke for this gun?

Try a 3" shell.

Try Hevi-Shot #6s or Nitro #7s

Try win hiv #5 or Federal #5 in the 3 inch load..

I would try a 3 inch also...I had real good lukc pattering the Winchester Extended shot this year...I used the 3 inch 6 shot..

What these guys are saying is that its a combination of shell and choke tube that makes a good pattern. Your Remington tube may not work with that particular shell/shot combination. I've never heard a good explanation why one tube works and one doesn't. Whether it's harmonics or matching the exact dia. of your barrel, it's a mystery. Try some different shells before giving up on your tube. You might even get a better pattern with 2 3/4" loads. My gun shoots #4's and #6's exceptionally, but won't shoot #5's consistantly. I don't know why, but I don't use #5's.