Any Aimpoint, or Aimpoint, or Aimpoint. Preferably a Micro.
I wouldn't trust any other brand of red dot
on my .454 for longevity, although I haven't broken my Docter
yet. For a magnified scope go with a Leupold
fixed or variable. That is about it. I have trusted others in the past and they let me down. If your .454 is a big, heavy, ported Super Redhawk you can probably get by with a Bushnell Elite
, but not on an unported Freedom Arms.