[arcticap]

The length isn't listed but it's probably a larger, heavier scope, especially with the large 50mm adjustable objective lens.
I recently bought a similar Simmons Whitetail Classic 6.5-20X50 A.O.. If I put it on a heavy barrel .308 it might really need a bipod. Or maybe I'll put it on a benchrest .22 LR for precision shooting at very small target dots.
If you're hunting long range then maybe the Simmons would be useful.
However when I recently bought a used Ruger M77 .308, it came with a 3-9X32 compact already mounted on it by the previous owner.
It's mostly about how much weight you want to carry for the intended purpose, and how high the scope will need to be mounted and whether that will be comfortable or not.
The front bell of a 40mm A.O. is even larger than a 40mm non-A.O. which can affect the scope mounting height.
And the length of the Simmons scope isn't listed which is a good thing to know [Check the Simmons website]. If the eye relief shrinks as the magnification is increased then that may not be as desirable either. The add states 3.75" eye relief which isn't too bad, but does it shrink?
BTW, the Simmons that I bought gets 4-5 stars from everyone because it regularly goes on clearance for about the same price as yours and has a pretty clear field of view, and it holds zero. But the field of view still isn't perfect, it has some distortion around the edges, and may need some A.O. adjustment in the field at higher magnification. There's probably better all round scopes for muzzle loading. Even a 4-12X40 A.O. would have plenty to offer.