I have one pistol with a scope it is a 45-70 encore with a Burris 1x however I have had a Burris 3-12x32 balistic plex on a .308 Encore pistol barrel and I was really not happy with that scope when you got above about 6x the eye relief was wrong for arms length. It would have been fine for a light caliber but nothing with recoil because the pistol would smack you between the eyes every time it went off and a balistic reticle only works at the highest power. I would stick with a low power, either the red dot aimpoint
which I think is best for hunting & target use or a 2x fixed Leupold or Burris. You will have to have a rest for anything with very much power. I really think the aimpoint would be perfect as we are talking a one hundred yard cartridge wiht a 454Casul. I sight in the 45-70 at 100 yds. If we were talking really flat rifle cartridge I would say more magnification but these are brush guns so you have to get on target quickly.