i will be a little more specific. i want a starting point with what choke/shell/shot combo to use for patterning my gun. i do not want to have a broken shoulder before season.
can i use 3" shells instead of 3 1/2"?

I have 2 of these guns. One has a 28" barrel the other a 24" barrel. I have a Kicks .685 choke in the longer one and it patterns best shooting 3.5 in. 2& 1/4 oz. Federal #4. The other gun has a Mossberg turkey choke at 675. It patterns best with 3.5 Winchester Supreme Velocity #4 in the 2oz. load and it also shoots Bismuth 1&7/8 oz. #2 a little tighter then the #4s. Both guns average about 30 hits in the head and neck with about 12 in the vital zones. The #2 Bismuth averages about 18 in the target with an average of 7 hits in the vital area. These were all patterned at 40 yards: at 20 yards the pattern is only about as big as a fist. I also get a good pattern using the choke for steelshot made by Mossberg that is marked full 2,BB and all lead. This choke averages about 22 & 8 respectively shooting the 2oz. 3.5 in Win. supreme high velocity #4s. Hope this helps.

for me and my gun the Winchester 3.5 #6 supreme regulars, not the HV shoot best out of my 24" barrel with an H.S. Strut Undertaker choke, at 40yds I don't know how many are in all of the head and neck but on a turkey target where it has a red circle around the brain I can put 14 pellets in that circle, I am not saying that this is nessarily good because there are some guys on here that are smoking that with thier set up but I will tell you from field expierence that it will get the job done every time, unless I do something stupid and miss. In short, it is a cheap and effective setup