Daryl the recoil energy estimated of your 12 Bore with round ball is 80 foot pounds and 24 fps recoil velocity. That Perrins calculates to about 147 foot pounds of recoil energy at 27 fps recoil velocity. See what I mean? A 9 pound .458 Winchester works out to 67 foot pounds with 22 fps recoil velocity. I will say that I was shooting an 8 pound .458 one day along with an 8 Bore W W Greener double rifle I used to own and the .458 hurt much more than the 8 Bore which was a huge push.