I like the way you used only 3553 fps for the 40-grain bullet in the .223 to calculate recoil, and 3701 with the 40-grain in the .204. In reality the .223 is capable of about 100 fps more velocity with 40's than the .204--which, of course, means the .223 will recoil more.
Do you actually load 40's down to about 3550 in the .223?
I think you are splitting hairs here. While the 223 shows slightly less recoil with said numbers, with same velocity it would still be close to same ft. lbs. recoil energy.
All numbers aside, I really can't notice any real world difference. Can see hits with either......
