From working in a physics dept. and testing every 3.5" turkey shell made in the last five years, it is very clear that a 3.5" shell was never intended to be shot from a 12 gauge shotgun. The barrel opening is simply not big enough for this type of charge to dissipate, thus creating severe recoil and punishment to the shooter. The 3.5" shell works great in a 10 gauge and even better in a 8 gauge if you dare.
The 3" shell is all you need in the 12 gauge so save yourself some pain and a lot of money a 3" shell will kill a turkey just as dead as the 3.5" shell while preserving your manhood and being a more accurate shooter.