SK330LC,
I have the same setup as you are describing. 12 inch Encore (SS) with DuoRing that was mounted once and forgotten. Last week, after probably 750 rounds, I noticed it was just a bit loose where the DuoRing base attaches to the barrel. Broke it all down and redid it with thread lock.
No more issues!
It has never lost its hold on the Elite 3200 scope it holds. I am having a tremendous amount of fun shooting it and have found that lighter loads work for me at this stage of my .44 mag career. I know you said you don't reload and I never had either until I got this rig.
Am finding that touching target holes is great fun and I can do that with my Alliant 2400 mid loads. I only mention this in case you know someone who loads and could do it for you or for under a $100 you could have everything you need to try it.
BTW, I shot it at 50, 100, 150 and 200 yard/meter silhouette targets 2 days ago and I see this will be great fun in the near future. I could not believe how close I was at 200 on the ram. Not that I would hunt that far but it will be a real skill builder.
Let us know how your shooting goes. Can't wait to hear how you like it after you have broken it in or shot something with it.
Mike