I have a Mossberg bolt action 12 gauge (model 695?)with a 2.5 Redfield on it that does 1.5" at 100 yards. I don't think they make it anymore. I've read a lot of exaggerated descriptions of bad triggers on these boards, but they are woefully inadequate to describe just how bad that Mossberg trigger truly is. I even sent it back to Mossberg and if they improved it, it is not discernable to me. This gun would disprove the notion that one needs a decent trigger to be accurate. It has a detachable 2 shot magazine that is cantankerous and has to be loaded very carefully to work. The safety is a LOUD click when taken off. Still, it is a shooter, pretty pleasant to carry, and has never failed me. I get the best groups with Federal-Barnes 3 inchers. Now that I wrote all of this - I think I'm gonna sell it.
Having said that, I have to give my vote to the NEF/H&R guns. I routinely get holes touching groups at 100 yards and the triggers are just great. They are safe, dependable, and accurate way beyond what I would expect for such a reasonable price. You can cock them silently too. And yes - they will shoot with the TarHunts. I am gravitating to muzzleloaders for my deer hunting, so the single shot H&R/NEF slug guns are a "fast reload" for me.
When I started hunting, most guys used a bird barrel and a foster type slug. 6" groups were good. I think Ithaca 37's were the best of the smoothbore sluggers then. Now the slug hunter has some awesome choices in guns and ammo. I bet that Savage bolt gun is a good one also.