It's pretty common for double guns of any brand to throw heavy turkey loads of hard shot somewhere other than pointed with at least one of the barrels. They're just not built for that. Lighter loads of lead or tungsten blends, etc are better.
I suggest looking at a Legacy or Stevens 28ga and plan on putting a red dot on. You'll probably end up aiming high for the bottom barrel, but you'll probably not often fire a second barrel at a gobbler.
Got any recommendations on red dot mounts?
AimTech Rib Rider, if it fits what you buy, will put a Picatinny rail on your rib. My last O/U I set up with a FastFire on a SumToy mount. I did bed the mount to the vent rib as the channel milled for the rib was a little generous. It has held up. Those are two I can vouch for working. There are others.
Aimpoint sells a red dot which mounts directly to the vent rib on shotguns.
