Ive seen you asking alot of questions lately, which is good, BUT!!! do your self a huge favor and slow it down and keep it simple. Dont be so quick to get to hung up on all the big patters and long ranges. This sport is tough and challenging but not rocket science. Take that 870 you have with the factory full choke, buy a box of premium turkey loads like LongBeards. Go shoot it, find your max range and move on to more important things. Ill bet money you will have a solid pattern out to 30 yards at least. Which is perfectly fine for probably 75% or more of the birds killed each year. Spend all that saved time on your calling and scouting. Go out and hunt, stick to your range and have FUN... Then after this seasons over start preparing early for the next if you really feel the need to improve things. Its just tough and exspensive to try and get all the latest gear a month or two before the opener. Good luck...
Just for the record, I have a plain old 870 express, and with its factory full choke it will put 140 in the 10 at 30 yards with el'cheapo Rem Nitros. I would hunt that setup any day of the season out to a max 35 yards and have no worries at all.