Mossberg 835 here. Slayed many a bird with it. I like the extra distance I get out of the 3.5" mag. Sounds unbelievable to me now, but I paid $269 for it NIB at Dicks Sporting Goods a few years back.
My 870 is 3.5"............but for turkey I just run 3". Do have some Magnum Blend extended range for it.