Re: Slug gun scope help.. Missed tonight.....
I have witnessed literally dozens of people shoot their smoothbores at the range and I will be the first to tell you that I have seen very few smoothbore guns/loads shoot well at 100 yards. I don't want to discourage you, but in my experience it is no small task to group well at 100 yards with a smoothbore, especially shooting the old school "pumpkinball" style slugs. The few I have seen accomplish this task were all shooting rifled slugs like the Brennekes. Again, i am not saying it is not possible, just that in my experience I have seen more smoothbores shoot unacceptable groups(for hunting) at 100 yards than I have seen put 3-4" groups from the bench.
The above advice is very good about playing around with different styles/brands of slugs. I have seen plenty of guns, even those of the same make/model, respond very differently to different rounds. It will be a long and possibly sore experience, but that is the only way you are going to determine your guns capabilities.
Is your scope mounted on the reciever or the barrel? If it is mounted on the reciever, you must remember that the barrel will always have some "play" in it, while the scope stays with the reciever. A cantilever mount moves with the play in the barrel and seems to eliminate this issue. However, I have also had some issues with cheap scopes not being able to handle the mule kicks that the slugs are famous for.
As far as the lightfields, they are saboted and while I am no gunsmithing guru, I don't see them performing very well in a smoothbore. They are intended to be shot from a rifled barrel, but maybe someone with some more knowledge here could chime in with their thoughts on the subject.
I currently shoot a 500 with a rifled cantilever barrel and a mid-grade scope. After trying a number of different slugs in the gun I found the lightfields to be the best from my gun. On a bench, I typically see about 3-4" groups at 100 yards.
I actually have a 12ga 500 rifled barrel that I would part with if you are interested. It has rifle sights on it, however the front sight is damaged and would need to be replaced(prob $7-10). PM if you would like as I have no need for it anymore.
Good luck and keep at it.